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   7041篇
  免费   623篇
  国内免费   9篇
耳鼻咽喉   62篇
儿科学   290篇
妇产科学   205篇
基础医学   1076篇
口腔科学   91篇
临床医学   1032篇
内科学   1089篇
皮肤病学   146篇
神经病学   615篇
特种医学   190篇
外科学   524篇
综合类   144篇
一般理论   7篇
预防医学   959篇
眼科学   305篇
药学   391篇
中国医学   6篇
肿瘤学   541篇
  2022年   43篇
  2021年   109篇
  2020年   64篇
  2019年   114篇
  2018年   119篇
  2017年   93篇
  2016年   114篇
  2015年   139篇
  2014年   168篇
  2013年   265篇
  2012年   358篇
  2011年   374篇
  2010年   192篇
  2009年   198篇
  2008年   350篇
  2007年   369篇
  2006年   405篇
  2005年   416篇
  2004年   410篇
  2003年   416篇
  2002年   365篇
  2001年   97篇
  2000年   95篇
  1999年   140篇
  1998年   99篇
  1997年   79篇
  1996年   81篇
  1995年   72篇
  1994年   50篇
  1993年   62篇
  1992年   80篇
  1991年   80篇
  1990年   80篇
  1989年   92篇
  1988年   94篇
  1987年   78篇
  1986年   83篇
  1985年   83篇
  1984年   66篇
  1983年   75篇
  1982年   67篇
  1981年   58篇
  1980年   43篇
  1979年   56篇
  1978年   43篇
  1977年   53篇
  1976年   42篇
  1974年   43篇
  1973年   45篇
  1972年   57篇
排序方式: 共有7673条查询结果,搜索用时 15 毫秒
71.
Bulimia nervosa in the male: a report of nine cases   总被引:1,自引:0,他引:1  
Nine male patients with bulimia nervosa, accounting for one in 24 bulimic patients attending a clinic for eating disorders, are described. Symptomatology and demographic characteristics were similar in males and females. A history of either anorexia nervosa or obesity was always present, and a chronic course was seen in 6 patients. Five of the men showed atypical sexuality.  相似文献   
72.
Patients with unilateral Horner's syndrome were studied to determine the influence of sympathetic innervation on the structure and function of the human cornea. There was no difference in total corneal thickness, corneal oxygen uptake rate or corneal touch threshold between the normal and Horner's eyes of these patients. Epithelial thickness, however, was slightly but significantly greater in the Horner's eye than in the normal fellow eye (P less than 0.025). When subjected to a hypoxic "Stress Test", patients with post-ganglionic lesions showed significantly more epithelial greying and microcystic oedema (P less than 0.025 and P less than 0.01, respectively) and reported seeing smaller and brighter haloes in the Horner's eye. The cornea of the affected eye of these patients also showed a significantly shower rate of deswelling in the first hour following the "Stress Test" (P less than 0.05). These findings suggest that both in the resting state and when the cornea is physiologically challenged, the sympathetic nervous system and in particular, the terminal sympathetic neuron, has a small but significant influence on the human corneal epithelium.  相似文献   
73.
Immunohistochemical techniques were used to determine the intermediate filament content of normal arachnoidal cells, meningiomas (including the so-called hemangiopericytoma of the meninges), soft tissue hemangiopericytoma, and the normal pericyte. Arachnoid granulations and all types of meningioma stained similarly: positive for vimentin and variably positive for keratin. Soft tissue hemangiopericytomas and normal pericytes were negative for both vimentin and keratin. This suggests that the "hemangiopericytoma" of the meninges is a variant of meningioma and not of pericytic origin.  相似文献   
74.
Adverse effects were evaluated in 48 myopic patients who wore low water content hydrogel lenses for an average of 48 +/- 19 weeks. Only one acute "red eye" occurred in the regular replacement group (2% of patients), whereas seven cases (15%) occurred in the non-replacement lens wearing eye. The major cause of clinical failure was giant papillary conjunctivitis (GPC), but the incidence was similar in both the replaced (15%) and non-replaced (15%) lens wearing eyes. These findings indicate that the acute red eye incidence can be reduced by regular replacement, that unilateral lens replacement does not reduce the incidence of GPC and that regularly replacing low water content lenses does not minimize the chronic corneal changes that occur during extended wear.  相似文献   
75.
IntroductionDetermining the efficacy of anti-scar technologies can be difficult as qualitative, subjective assessments are often utilized instead of systematic, objective measures. Perceptions regarding the reliability of instruments for quantitative measurements along with their high cost and increased data collection time may discourage their use, leading to use of scar scales which are relatively quick and low-cost. To directly evaluate the reliability of instruments for quantitative measurements of scar properties, instruments and two qualitative scales were compared by assessing a variety of cutaneous scars.MethodsScar height and surface texture were evaluated using a 3D scanner and a mold/cast technique. Scar color was evaluated by using a spectroscopy-based tool, the Mexameter®, and digital photography with image analysis. Scar biomechanics were evaluated using the BTC-2000?, Dermal Torque Meter (DTM®), and ballistometer®. The Vancouver Scar Scale (VSS) and Patient and Observer Scar Assessment Scale (POSAS) were used to qualitatively evaluate the same scar properties. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-user reliability (poor, moderate, good, excellent) with all instruments and the kappa reliability statistic was used to asses inter-user reliability (poor, fair, moderate, good, very good) for VSS and POSAS. Time for measurement collection and after collection analysis was also recorded.ResultsThe Mexameter® was the most reliable method for evaluating erythema and pigmentation compared to digital photography and image processing, POSAS and VSS. Digital photography and analysis was more reliable than POSAS and VSS. Assessment of scar height was significantly more reliable when using a 3D scanner versus VSS and POSAS. The 3D scanner and mold-cast techniques also offered an additional benefit of providing an absolute value of scar height relative to the surrounding tissue. Intra-user reliability for all mechanical tests was moderate to good. Inter-user reliability was greater when using the BTC-2000? and ballistometer® versus the DTM®. All quantitative measurements took less than 90 s for collection, with the exception of the mold/cast technique.ConclusionNon-invasive instruments allow scar properties to be quantitatively assessed with high sensitivity and as a function of time and/or treatment without the need for biopsy collection. Overall, the reliability of scar assessments was significantly improved when quantitative instruments were utilized versus scar scales. Quantitative assessment of color and biomechanics were swift, requiring less than 90 s per measurement while assessments of texture and height required additional analysis time after collection. With proper training of clinical staff and well-defined protocols for measurement collection, reliable, quantitative assessments of scar properties can be collected with little disruption to the clinical workflow.  相似文献   
76.
PurposeThe objective of this quality improvement (QI) initiative was to implement a standardized clinical treatment protocol for patients presenting with primary spontaneous pneumothorax (PSP) in order to decrease hospital length of stay (LOS), diagnostic radiation exposure, and related cost.MethodsBaseline data from patients admitted with PSP from January 1, 2016 to July 31, 2018 were compared to data from patients managed using a newly developed evidence-based treatment pathway from August 1, 2018 to December 31, 2019. Standard QI methodology was used to track results.ResultsFifty-six episodes of PSP were observed during the baseline period and 40 episodes of PSP following initiation of the PSP protocol. The average LOS decreased from 4.5 days to 2.9 days. Patients underwent an average of 8.8 X-rays per admission preintervention versus 5.9 postintervention. The rate of CT scans decreased from 45% to 15% (p = 0.002). There was no significant difference in the rates of 30-day recurrence between the preintervention (13%) and postintervention (10%) groups (p = 0.7). Average admission costs per patient decreased by $1322 after adoption of the pathway.ConclusionsAdoption of a standardized treatment protocol for PSP led to a reduction in LOS, diagnostic imaging utilization, and cost without increasing clinical recurrence.Type of studyQuality improvement.Level of evidenceLevel III.  相似文献   
77.
IntroductionThe human immunodeficiency virus 1 (HIV‐1) pandemic is characterized by numerous distinct sub‐epidemics (clusters) that continually fuel local transmission. The aims of this study were to identify active growing clusters, to understand which factors most influence the transmission dynamics, how these vary between different subtypes and how this information might contribute to effective public health responses.MethodsWe used HIV‐1 genomic sequence data linked to demographic factors that accounted for approximately 70% of all new HIV‐1 notifications in New South Wales (NSW). We assessed differences in transmission cluster dynamics between subtype B and circulating recombinant form 01_AE (CRF01_AE). Separate phylogenetic trees were estimated using 2919 subtype B and 473 CRF01_AE sequences sampled between 2004 and 2018 in combination with global sequence data and NSW‐specific clades were classified as clusters, pairs or singletons. Significant differences in demographics between subtypes were assessed with Chi‐Square statistics.ResultsWe identified 104 subtype B and 11 CRF01_AE growing clusters containing a maximum of 29 and 11 sequences for subtype B and CRF01_AE respectively. We observed a > 2‐fold increase in the number of NSW‐specific CRF01_AE clades over time. Subtype B clusters were associated with individuals reporting men who have sex with men (MSM) as their transmission risk factor, being born in Australia, and being diagnosed during the early stage of infection (p < 0.01). CRF01_AE infections clusters were associated with infections among individuals diagnosed during the early stage of infection (p < 0.05) and CRF01_AE singletons were more likely to be from infections among individuals reporting heterosexual transmission (p < 0.05). We found six subtype B clusters with an above‐average growth rate (>1.5 sequences / 6‐months) and which consisted of a majority of infections among MSM. We also found four active growing CRF01_AE clusters containing only infections among MSM. Finally, we found 47 subtype B and seven CRF01_AE clusters that contained a large gap in time (>1 year) between infections and may be indicative of intermediate transmissions via undiagnosed individuals.ConclusionsThe large number of active and growing clusters among MSM are the driving force of the ongoing epidemic in NSW for subtype B and CRF01_AE.  相似文献   
78.
Journal of Community Health - While human papilloma virus (HPV) vaccinations and Pap smear screenings are known to improve the survival rates and incidence of cervical cancer, refugee populations...  相似文献   
79.
80.
Tetrahydrocortisol, -cyclodextrin tetradecasulfate, and minocycline used alone or in combination are not very cytotoxic toward EMT-6 mouse mammary tumor cells growing in monolayer. Tetrahydrocortisol (100 M, 24 h) and -cyclodextrin tetradecasulfate (100 M, 24 h) protected EMT-6 cells from the cytotoxicity of CDDP, melphalan, 4-hydroperoxycyclophosphamide, BCNU, and X-rays under various conditions of oxygenation and pH. Minocycline (100 M, 24 h) either had no effect upon or was additive with the antitumor alkylating agents or X-rays in cytotoxic activity toward the EMT-6 cells in culture. The combination of the three modulators either had no effect upon or was to a small degree protective against the cytotoxicity of the antitumor alkylating agents or X-rays. The Lewis lung carcinoma was chosen for primary tumor growth-delay studies and tumor lung-metastases studies. Tetrahydrocortisol and -cyclodextrin tetradecasulfate were given in a 1:1 molar ratio by continuous infusion over 14 days, and minocycline was given i.p. over 14 days, from day 4 to day 18 post tumor implantation. The combination of tetrahydrocortisol/-cyclodextrin tetradecasulfate diminished the tumor growth delay induced by CDDP and melphalan and produced modest increases in the tumor growth delay produced by cyclophosphamide and radiation. Minocycline co-treatment increased the tumor growth delay produced by CDDP, melphalan, radiation, bleomycin, and, especially cyclophosphamide, where 4 of 12 animals receiving minocycline (14×5mg/kg, days 4–18) and cyclophosphamide (3×150 mg/kg, days, 7, 9, 11) were long-term survivors. The 3 modulators given in combination produced further increases in tumor growth delay with all of the cytotoxic therapies, and 5 of 12 of the animals treated with the 3-modulator combination and cyclophosphamide were long-term survivors. Although neither tetrahydrocortisol/-cyclodextrin tetradecasulfate, minocycline, nor the three modulator combination impacted the number of lung metastases, there was a decrease in the number of large lung metastases. Treatment with the cytotoxic therapies alone reduced the number of lung metastases. Addition of the modulators to treatment with the cytotoxic therapies resulted in a further reduction in the number of lung metastases. These results indicate that agents that inhibit the breakdown of the extracellular matrix can be useful additions to the treatment of solid tumors.Abbreviations 14(SO4)ßCD -cyclodextrin tetradecasulfate - THC tetrahydrocortisol - CDDP cis-diamminedichloroplatinum(II) - 4-HC 4-hydroperoxycyclophosphamide - BCNU N,N-bis(2-chloroethyl)-N-nitrosourea - CAM chick embryo chorioallantoic membrane; IC50, concentration of a drug required to kill 50% of the cells This work was supported by NIH grant P01-CA38493 and a grant from Bristol-Myers-Squibb, Inc., Wallingford, Connecticut  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