首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   14833篇
  免费   1193篇
  国内免费   62篇
耳鼻咽喉   97篇
儿科学   340篇
妇产科学   220篇
基础医学   2017篇
口腔科学   252篇
临床医学   2006篇
内科学   2747篇
皮肤病学   181篇
神经病学   1397篇
特种医学   622篇
外国民族医学   1篇
外科学   2385篇
综合类   286篇
现状与发展   1篇
一般理论   9篇
预防医学   1241篇
眼科学   233篇
药学   1097篇
中国医学   50篇
肿瘤学   906篇
  2023年   75篇
  2022年   124篇
  2021年   254篇
  2020年   154篇
  2019年   239篇
  2018年   327篇
  2017年   229篇
  2016年   226篇
  2015年   269篇
  2014年   444篇
  2013年   547篇
  2012年   907篇
  2011年   1059篇
  2010年   497篇
  2009年   488篇
  2008年   772篇
  2007年   914篇
  2006年   752篇
  2005年   830篇
  2004年   722篇
  2003年   704篇
  2002年   687篇
  2001年   310篇
  2000年   340篇
  1999年   318篇
  1998年   188篇
  1997年   159篇
  1996年   150篇
  1995年   130篇
  1994年   115篇
  1993年   114篇
  1992年   225篇
  1991年   179篇
  1990年   183篇
  1989年   178篇
  1988年   166篇
  1987年   184篇
  1986年   142篇
  1985年   188篇
  1984年   153篇
  1983年   115篇
  1982年   100篇
  1981年   105篇
  1980年   82篇
  1979年   107篇
  1978年   91篇
  1977年   79篇
  1976年   77篇
  1974年   76篇
  1972年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The in vitro invasive behaviour of six meningioma cell lines of various histological sub-type and grade was assessed using Boyden chemotaxis chambers ('Transwell' units) precoated with various extracellular matrix proteins. The cell lines included a benign meningothelial (IPGS), two benign transitional (IPCBR and IPGC), one atypical (IPIH) and two malignant (IPSE and IPIR) meningiomas. IPGC was a recurrent tumour. The results showed that IPCBR was most invasive through laminin and vitronectin. IPIH was moderately invasive through collagen type IV, laminin, vitronectin and fibronectin. However, both IPSE and IPIR were less invasive than IPIH whereas, IPGS was least invasive of all. Moreover, laminin was the most permissive extracellular matrix protein for most cell lines and collagen type IV, the least permissive. These results show that there is a differential in vitro invasive behaviour of cell lines derived from different histological types of meningiomas according to extracellular matrix substrate and suggests that invasion and migration of meningiomas in situ might be modulated by various extracellular components.  相似文献   
92.
Summary We compared doxorubicin and metabolite pharmacokinetic data obtained from thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) assay of plasma samples from six patients who had been treated with doxorubicin. Duplicate 1-ml samples were extracted with chloroform: isopropanol (1:1) and assayed using a sensitive HPLC system incorporating a dual pump gradient with tetrahydrofuran as the mobile phase and fluorescence detection. Duplicate 1-ml samples from the same specimens were assayed using a modification of a previously described TLC assay. Areas under the curve for doxorubicin by HPLC (3.36±2.30 M · h) and TLC (4.16±2.50 M · h) were not significantly different (P=0.5). Terminal half-life of doxorubicin by HPLC (28.0±6.98 h) and TLC (23.2±7.8) (P=0.29) and the calculated total-body clearances by HPLC (0.55±0.29 l/min) and TLC (0.45±0.23) (P=0.55) were not significantly different. Areas under the curve for doxorubicinol by HPLC (2.75±1.4 M · h) and TLC (2.53±7.1 M · h) (P=0.73) showed no significant differences. HPLC detected a mixed 7-deoxydoxorubicinol aglycone-doxorubicin aglycone peak, 7-deoxydoxorubicin aglycone, and two nonpolar, unidentified metabolites. TLC detected the following aglycone metabolites: doxorubicin aglycone, doxorubicinol aglycone, 7-deoxydoxorubicinol aglycone, an unidentified polar metabolite, and several unidentified nonpolar metabolites. From these data we conclude that HPLC and TLC detect concentrations of doxorubicin and doxorubicinol from human plasma equally well to concentrations of 7.0 nM (4 pmol injected doxorubicin). Aglycones do circulate in human plasma at concentrations above the detection limits of both assays. Doxorubicinol aglycone, which is detected by TLC but not by HPLC, may be formed from artifactual breakdown of doxorubicinol during TLC development. Unidentified nonpolar compounds seen on HPLC and TLC may represent further doxorubicin metabolism than previously described.  相似文献   
93.
For bereavement research to fulfill its potential, its practical applications with defined patient groups needs to demonstrate a superiority over treatment based largely on intuition and common sense. The "art" of the therapist needs science to move beyond the present impasse in the management of bereavement.  相似文献   
94.
Some studies have reported that stimulation of the superior colliculus in rats produces orienting responses, as it does in a number of species. However, other studies have reported movements resembling avoidance and escape, which are not characteristic of collicular stimulation in other mammals. This apparent discrepancy was investigated by systematically recording the effects on head and body movements of electrical stimulation at a large number of sites throughout the superior colliculus (SC) and surrounding structures. It was found that the nature of the movements observed depended on the location of the stimulating electrode. Contralateral head and body movements resembling orienting and approach were obtained from sites in the intermediate and deep layers in rostral colliculus, the intermediate white layer and immediately surrounding tissue in central colliculus, and in all layers except deep white in caudal colliculus. At the remaining responsive sites, movements resembling avoidance and escape were obtained. The most common response was an ipsilateral cringelike movement of the body that developed into ipsilateral locomotion, followed by running and jumping as the current was increased. These movements were obtained from sites in the superficial and intermediate layers rostrally; from the intermediate gray and the medial superficial and deep layers in central colliculus; and from the deep layers and underlying tegmentum caudally. The distributions of sites, together with evidence from other studies, suggested the following conclusions: Within the superficial layers, avoidance responses were obtained from a region of the superior colliculus that appeared to represent the upper visual field, whereas orienting responses were obtained from a region apparently representing the lower visual field. Stimulation of the area containing the cells of origin of the predorsal bundle produced orientation and approach movements, whereas the avoidance and escape movements were probably mediated by parts of the ipsilateral descending pathway. The stimulation-induced avoidance and escape may reflect the importance of such responses to visual "events," particularly in the upper part of the visual field, in animals, like rats, with many predators.  相似文献   
95.
BackgroundConsumer genomic testing for nutrition and wellness, (nutritional genomics), is becoming increasingly popular. Concurrently, health‐care practitioners (HPs) working in private practice (including doctors interested in integrative medicine, private genetic counsellors, pharmacists, dieticians, naturopaths and nutritionists) are involved as test facilitators or interpreters.ObjectiveTo explore Australian consumers’ and HPs’ experiences with nutrigenomic testing.MethodSemi‐structured in‐depth interviews were conducted using predominantly purposive sampling. The two data sets were analysed individually, then combined, using a constant comparative, thematic approach.ResultsOverall, 45 interviews were conducted with consumers (n = 18) and HPs (n = 27). Many of the consumer interviewees experienced chronic ill‐health. Nutrigenomic testing was perceived as empowering and a source of hope for answers. While most made changes to their diet/supplements post‐test, self‐reported health improvements were small. A positive relationship with their HP appeared to minimize disappointment. HPs’ adoption and views of nutrigenomic testing varied. Those enthusiastic about testing saw the possibilities it could offer. However, many felt nutrigenomic testing was not the only ‘tool’ to utilize when offering health care.DiscussionThis research highlights the important role HPs play in consumers’ experiences of nutrigenomics. The varied practice suggests relevant HPs require upskilling in this area to at least support their patients/clients, even if nutrigenomic testing is not part of their practice.Patient or public contributionAdvisory group included patient/public group representatives who informed study design; focus group participants gave feedback on the survey from which consumer interviewees were sourced. This informed the HP data set design. Interviewees from HP data set assisted with snowball sampling.  相似文献   
96.
Complete genomic screen in Parkinson disease: evidence for multiple genes.   总被引:28,自引:1,他引:27  
CONTEXT: The relative contribution of genes vs environment in idiopathic Parkinson disease (PD) is controversial. Although genetic studies have identified 2 genes in which mutations cause rare single-gene variants of PD and observational studies have suggested a genetic component, twin studies have suggested that little genetic contribution exists in the common forms of PD. OBJECTIVE: To identify genetic risk factors for idiopathic PD. DESIGN, SETTING, AND PARTICIPANTS: Genetic linkage study conducted 1995-2000 in which a complete genomic screen (n = 344 markers) was performed in 174 families with multiple individuals diagnosed as having idiopathic PD, identified through probands in 13 clinic populations in the continental United States and Australia. A total of 870 family members were studied: 378 diagnosed as having PD, 379 unaffected by PD, and 113 with unclear status. MAIN OUTCOME MEASURES: Logarithm of odds (lod) scores generated from parametric and nonparametric genetic linkage analysis. RESULTS: Two-point parametric maximum parametric lod score (MLOD) and multipoint nonparametric lod score (LOD) linkage analysis detected significant evidence for linkage to 5 distinct chromosomal regions: chromosome 6 in the parkin gene (MLOD = 5.07; LOD = 5.47) in families with at least 1 individual with PD onset at younger than 40 years, chromosomes 17q (MLOD = 2.28; LOD = 2.62), 8p (MLOD = 2.01; LOD = 2.22), and 5q (MLOD = 2.39; LOD = 1.50) overall and in families with late-onset PD, and chromosome 9q (MLOD = 1.52; LOD = 2.59) in families with both levodopa-responsive and levodopa-nonresponsive patients. CONCLUSIONS: Our data suggest that the parkin gene is important in early-onset PD and that multiple genetic factors may be important in the development of idiopathic late-onset PD.  相似文献   
97.
CONTEXT: The human tau gene, which promotes assembly of neuronal microtubules, has been associated with several rare neurologic diseases that clinically include parkinsonian features. We recently observed linkage in idiopathic Parkinson disease (PD) to a region on chromosome 17q21 that contains the tau gene. These factors make tau a good candidate for investigation as a susceptibility gene for idiopathic PD, the most common form of the disease. OBJECTIVE: To investigate whether the tau gene is involved in idiopathic PD. DESIGN, SETTING, AND PARTICIPANTS: Among a sample of 1056 individuals from 235 families selected from 13 clinical centers in the United States and Australia and from a family ascertainment core center, we tested 5 single-nucleotide polymorphisms (SNPs) within the tau gene for association with PD, using family-based tests of association. Both affected (n = 426) and unaffected (n = 579) family members were included; 51 individuals had unclear PD status. Analyses were conducted to test individual SNPs and SNP haplotypes within the tau gene. MAIN OUTCOME MEASURE: Family-based tests of association, calculated using asymptotic distributions. RESULTS: Analysis of association between the SNPs and PD yielded significant evidence of association for 3 of the 5 SNPs tested: SNP 3, P =.03; SNP 9i, P =.04; and SNP 11, P =.04. The 2 other SNPs did not show evidence of significant association (SNP 9ii, P =.11, and SNP 9iii, P =.87). Strong evidence of association was found with haplotype analysis, with a positive association with one haplotype (P =.009) and a negative association with another haplotype (P =.007). Substantial linkage disequilibrium (P<.001) was detected between 4 of the 5 SNPs (SNPs 3, 9i, 9ii, and 11). CONCLUSIONS: This integrated approach of genetic linkage and positional association analyses implicates tau as a susceptibility gene for idiopathic PD.  相似文献   
98.
99.
Background/PurposeCervicofacial lymphatic malformations (CFLM) are rare, potentially life-threatening vascular anomalies, yet reports on multidisciplinary treatment strategies are lacking. We evaluated outcomes for CFLMs following sclerotherapy, surgical resection, and/or medical management.MethodsWe identified children with a CFLM at a vascular anomalies center from 2004 to 2019. Exclusion criteria: retro-orbital malformations, untreated malformations, patients without follow-up. Primary clinical outcome was contour improvement, with significance defined as LM volume reduction of > 50% by cross-sectional imaging.ResultsSixty-three children met inclusion criteria: 35 with macrocystic CFLMs, six with microcystic CFLMs, and 22 with mixed-type malformations. Mean post-intervention follow-up was 27.5 months. Fifty-eight patients underwent sclerotherapy (median: two treatments). Doxycycline and/or bleomycin were used in 95% of patients. After sclerotherapy, 97% of macrocystic CFLMs improved significantly compared to 82% of mixed and 67% of microcystic lesions. Sixteen children underwent surgical resection with 75% significantly improving; two additional patients were successfully treated with sclerotherapy after debulking surgery. Six children received sirolimus for microcystic disease, of which 33% significantly improved.ConclusionSclerotherapy is very effective for macrocystic components of CFLMs, albeit less so for microcystic disease. Microcystic CFLMs frequently require surgical resection. Sirolimus is a helpful therapeutic adjunct, particularly for microcystic lesions, but more study is needed.Level of EvidenceLevel II, prognosis study  相似文献   
100.
Study Design: Systematic review and meta-analysis.Objective: To compare the effectiveness and safety between anterior and posterior approach, and determine the best surgical methods for the treatment of ossification of the posterior longitudinal ligament (OPLL) in the cervical spine.Methods: We searched the Cochrane Library, PubMed, CNKI and Wanfang Med Data databases from January 2007 to March 2018. Japanese Orthopaedic Association (JOA) scores, cervical lordosis, functional recovery rates, excellent and good outcomes of the surgical approaches, and complication and reoperation rates were analyzed. RevMan 5.3 was utilized for data analysis.Results: Eleven studies were included in the meta-analysis. By comparing the anterior and posterior approaches for the treatment of OPLL in the cervical spine, statistically significant differences were found in the preoperative initial JOA, the postoperative final JOA scores, functional recovery rates, complication rates, excellent and good outcomes of the surgical approaches and reoperation rates. However, no statistically significant difference in the occurrence of the preoperative and postoperative cervical lordosis was noted.Conclusion: The anterior approach is superior to the posterior approach in terms of the postoperative final JOA score, functional recovery rate, and clinical outcomes. Although the complication and reoperation rates of the anterior approach are higher than those of the posterior approach. We recommend the anterior approach for the treatment of OPLL when patients with occupying ratio ≥ 60%. In addition, high-quality studies with long-term follow-up and large sample size are also needed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号