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   12356篇
  免费   1361篇
  国内免费   31篇
耳鼻咽喉   148篇
儿科学   295篇
妇产科学   301篇
基础医学   1698篇
口腔科学   405篇
临床医学   1793篇
内科学   2032篇
皮肤病学   214篇
神经病学   1081篇
特种医学   398篇
外国民族医学   3篇
外科学   1818篇
综合类   313篇
一般理论   9篇
预防医学   1149篇
眼科学   210篇
药学   1034篇
中国医学   10篇
肿瘤学   837篇
  2021年   131篇
  2019年   145篇
  2018年   180篇
  2017年   153篇
  2016年   155篇
  2015年   174篇
  2014年   237篇
  2013年   371篇
  2012年   495篇
  2011年   522篇
  2010年   302篇
  2009年   317篇
  2008年   493篇
  2007年   564篇
  2006年   545篇
  2005年   499篇
  2004年   495篇
  2003年   465篇
  2002年   512篇
  2001年   478篇
  2000年   493篇
  1999年   425篇
  1998年   151篇
  1997年   127篇
  1996年   144篇
  1995年   148篇
  1994年   146篇
  1993年   122篇
  1992年   295篇
  1991年   295篇
  1990年   287篇
  1989年   253篇
  1988年   260篇
  1987年   244篇
  1986年   254篇
  1985年   252篇
  1984年   188篇
  1983年   156篇
  1981年   115篇
  1980年   96篇
  1979年   177篇
  1978年   113篇
  1977年   112篇
  1976年   105篇
  1975年   93篇
  1974年   108篇
  1973年   108篇
  1972年   110篇
  1971年   98篇
  1968年   113篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Narrative and procedural discourse in temporal lobe epilepsy.   总被引:2,自引:0,他引:2  
It is well established that some individuals with temporal lobe epilepsy (TLE) demonstrate language deficits at the single word level. However, discourse production rarely has been examined quantitatively within this group. This study compared adult TLE patients with an early seizure onset (< or = age 14 years, n = 27) to a control group (n = 28) on narrative and procedural discourse tasks. As a group, the TLE patients performed normally on the procedural discourse task, but differed significantly from the controls on several narrative discourse variables. At the individual level, 30% of the TLE patients versus 4% of the controls demonstrated impaired discourse ability (p and 0.01). Within this early onset TLE group, discourse performance was not associated with demographic or seizure history variables. Considering the cognitive domain, discourse performance correlated significantly with working memory. In summary, mild discourse dysfunction was present in a significant minority of early onset TLE patients, but this deficit was not closely associated with other language measures. Discourse ability and its neuropsychological, neuroanatomical and conversational speech correlates deserve further study in TLE patients.  相似文献   
102.
The objective of this study was to establish to what extent muscle, cutaneous, and joint afferents alter the excitability of spinal and cortical motor neurons. This question was examined by studying the impact of electrical stimulation of the second and third digits, the median nerve at the wrist, and the recurrent thenar motor branch on the F/H and magneto-electrical cortical motor responses (MEPs) of the thenar muscles. The firing frequencies of single F/H motor unit action potentials were unaltered by the foregoing conditioning peripheral stimuli. MEPs conditioned by motor threshold stimulation of the median nerve at the wrist or the recurrent motor branch were significantly increased in size at conditioning to test intervals of 50 to 80 milliseconds. No significant change in MEP size resulted from conditioning stimulation of the digital nerves. We conclude that muscle afferents were primarily responsible for the increase in MEP size. Conditioning stimuli may allow examiners to assess central motor conduction where it would otherwise be impossible.  相似文献   
103.
OBJECTIVE: We investigated whether monocyte-derived factors could stimulate the growth of ovarian cancer cells. STUDY DESIGN: Human peripheral blood monocytes or human monocyte-like cell lines THP-1 and U-937 were cultured with or without macrophage colony-stimulating factor, lipopolysaccharide, or phorbol myristate acetate. Culture supernatants or recombinant cytokines were assayed for growth stimulation of ovarian cancer cell lines by tritium-thymidine incorporation and direct cell counts followed by statistical analysis with Student t test. RESULTS: Conditioned medium from peripheral blood monocytes or from THP-1 or U-937 cells stimulated ovarian cancer cell growth. Interleukin-1 alpha, tumor necrosis factor-alpha, and interleukin-6 also stimulated ovarian cancer cell growth, whereas macrophage, granulocyte, and granulocyte-macrophage colony-stimulating factor did not. Concentrations of tumor necrosis factor, interleukin-1, and interleukin-6 in conditioned medium could not account for all the growth stimulation, and activity remained after neutralization of tumor necrosis factor, interleukin-1, and interleukin-6 with antibodies. CONCLUSIONS: Interleukin-1, interleukin-6, tumor necrosis factor, and additional monocyte factor(s) could provide paracrine growth stimulation when monocytes are attracted to ovarian cancers that produce macrophage colony-stimulating factor.  相似文献   
104.
We report a case of eosinophilic cystitis that was responsive to prednisone but that recurred when the drug was withdrawn. The cause of eosinophilic cystitis remains an enigma but it probably represents a form of allergy. Investigation of etiology and therapeutic options are discussed.  相似文献   
105.
In the event of an unplanned release of a chemical warfare agent during any stage of the Chemical Stockpile Disposal Program, the potential exists for off-post contamination of drinking water, forage crops, grains, garden produce, and livestock. The more persistent agents, such as the organophosphate nerve agent VX, pose the greatest human health concern for reentry. A relative potency approach comparing the toxicity of VX to organophosphate insecticide analogues is developed and used to estimate allowable residues for VX in agricultural products and reentry intervals for public access to contaminated areas. Analysis of mammalian LD50 data by all exposure routes indicates that VX is 10(3) to 10(4) times more toxic than most commercially available organophosphate insecticides. Thus, allowable residues of VX could be considered at concentration levels 10(3) to 10(4) lower than those established for certain insecticides by the U.S. EPA. Evaluation of reentry intervals developed for these organophosphate analogues indicate that, if environmental monitoring cannot reliably demonstrate acceptable levels of VX, restricted access to suspect or contaminated areas may be on the order of weeks to months following agent release. Planning for relocation, mass care centers, and quarantine should take this time period into account.  相似文献   
106.
A near-patient testing facility was provided at an anticonvulsant clinic and compared with the previously offered service. Productivity was increased by over 20%, with savings in medical and nursing staff time. This saving in time is offset by increased consumable costs but still enables a significant net saving.  相似文献   
107.
Survival of random skin flap distal end depends on hemodynamic, cellular, and coagulation mechanisms. This study was designed to evaluate whether administration of ciprostene, a stable prostaglandin I2 analogue, and indomethacin, a cyclooxygenase-hydroperoxydase enzyme inhibitor, would improve the survival rate of random skin flaps. Forty-five male rats were divided into nine groups and injected with sesame oil (control), ciprostene (20 micrograms/kg/day), and/or indomethacin (2 mg/kg/day). Injections were done before (pretreatment for 4 days), after (posttreatment for 6 days), and before/after (pre/posttreatment for 4 and 6 days, respectively) the elevation of random dorsal skin flaps. In the pretreatment and pre/posttreatment studies, the flap survival rate of all drug-injected groups was significantly higher than that of the control group (p less than 0.02). In addition administration of ciprostene alone yielded a trend of better flap survival rate, which, however, was not statistically significant (p less than 0.12). Of interest in the posttreatment study, only the simultaneous administration of ciprostene and indomethacin significantly increased skin flap viability compared with the other groups (p less than 0.02). Therefore, the results demonstrated that administration of ciprostene and indomethacin either alone or together partially reversed the pathophysiological mechanisms that cause necrosis of random skin flap distal end. These pharmacological changes significantly improved random skin flap survival rate.  相似文献   
108.
Multiple reports of cauda equina syndrome and transient radicular nerve root irritation have suggested that lidocaine spinal anesthesia may be responsible. In this case report, a patient with a preexisting diabetic neuropathy received a partial block following a tetracaine spinal, which was followed by a lidocaine spinal. Following block resolution, a new conus medullaris syndrome was diagnosed. Because of the close proximity of the cauda equina and the conus medullaris, differentiation between these syndromes can be difficult. The preexisting diabetic neuropathy may have predisposed this patient to neurologic injury. The choice of a different local anesthetic drug with less neurotoxic potential such as bupivacaine may have prevented this injury.  相似文献   
109.
Eight individuals with Alzheimer's disease, and eight age-matched controls, were administered the MMSE, the Yesavage GDS, and a customized subset of the Automated Neuropsychological Assessment Metrics (ANAM) Battery. Accuracy (percent correct) and efficiency (number of correct responses per minute) of performance on six ANAM tasks were assessed. The patients' GDS scores indicated no depression. Although their MMSE scores (mean approximately 25) were significantly lower than those of the controls, they nonetheless indicated that the patients were still functioning at a fairly high level. Analysis of ANAM accuracy scores indicated that the patients were significantly impaired on three tasks measuring working memory. A discriminant function analysis revealed 93.8% correct classification. Analysis of ANAM efficiency scores revealed that except for simple reaction time, the patients were significantly impaired on all tasks. A discriminant function analysis correctly classified 100% of the participants. Given the small size of the groups in the present study, this finding especially underscores the sensitivity of ANAM to the cognitive effects of Alzheimer's disease, as indicated by the large effect sizes. The findings further indicate that ANAM might be capable of detecting more subtle effects of the disease at an earlier stage in its progress.  相似文献   
110.
The α-inhibin gene has been shown in knockout mouse models to be a suppressor of granulosa tumorigenesis in the mouse. To determine if α-inhibin has the same function in humans, we have assessed the frequency of loss of heterozygosity (LOH) of the α-inhibin gene locus on chromosome 2q in 17 human granulosa cell tumors and 36 epithelial ovarian cancers. LOH was detected in 12 of 36 (33.3%) epithelial tumors but in only 1 of 17 (6%) granulosa cell tumors. These data suggest that in contrast to the suggestions from the mouse model α-inhibin does not function as a granulosa cell tumor suppressor gene in the human. Furthermore, analysis of the TP53 gene in the granulosa cell tumors failed to detect either LOH or point mutations, indicating that they have a developmental pathway distinct from that of epithelial ovarian tumors.  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