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   8799篇
  免费   620篇
  国内免费   30篇
耳鼻咽喉   155篇
儿科学   235篇
妇产科学   175篇
基础医学   1022篇
口腔科学   164篇
临床医学   1105篇
内科学   1618篇
皮肤病学   125篇
神经病学   731篇
特种医学   433篇
外国民族医学   2篇
外科学   1177篇
综合类   161篇
一般理论   11篇
预防医学   1005篇
眼科学   220篇
药学   602篇
中国医学   13篇
肿瘤学   495篇
  2022年   92篇
  2021年   196篇
  2020年   127篇
  2019年   168篇
  2018年   172篇
  2017年   133篇
  2016年   157篇
  2015年   200篇
  2014年   277篇
  2013年   354篇
  2012年   480篇
  2011年   479篇
  2010年   282篇
  2009年   262篇
  2008年   433篇
  2007年   402篇
  2006年   361篇
  2005年   389篇
  2004年   298篇
  2003年   303篇
  2002年   292篇
  2001年   204篇
  2000年   209篇
  1999年   207篇
  1998年   123篇
  1997年   115篇
  1996年   98篇
  1995年   89篇
  1994年   98篇
  1993年   71篇
  1992年   141篇
  1991年   132篇
  1990年   156篇
  1989年   129篇
  1988年   130篇
  1987年   130篇
  1986年   120篇
  1985年   120篇
  1984年   99篇
  1983年   79篇
  1982年   75篇
  1981年   66篇
  1979年   83篇
  1978年   75篇
  1977年   51篇
  1976年   57篇
  1975年   64篇
  1973年   63篇
  1972年   55篇
  1969年   54篇
排序方式: 共有9449条查询结果,搜索用时 15 毫秒
91.
Retinitis pigmentosa, of unknown cause, has recently been associated with decreased amounts of the polyunsaturated fatty acid, docosahexaenoic acid, in the plasma of affected as compared with unaffected relatives. It has been suggested that this finding may serve as a marker for the disease and might indicate alterations in photoreceptor cell metabolism. The authors studied 54 members of a family with dominantly inherited retinitis pigmentosa in five generations. In addition to the typical clinical findings of retinitis pigmentosa, eight persons also had a bull's eye maculopathy, and four persons had uni- or bilateral optic nerve drusen. When the authors determined the plasma fatty acid and lipid contents, they saw the expected age-related effect on cholesterol and triglycerides, but an unexpected, significant reduction in fatty acids in the unaffected controls as compared with persons with retinitis pigmentosa. The authors' results emphasize the heterogeneity of phenotypic expression of retinitis pigmentosa within a single family.  相似文献   
92.
Threshold Amsler grid testing in maculopathies   总被引:1,自引:0,他引:1  
M Wall  D R May 《Ophthalmology》1987,94(9):1126-1133
The Amsler grid is a suprathreshold target and thus may fail to detect relative scotomas. If the grid is viewed through two cross-polarizing filters creating low luminance conditions (threshold Amsler grid testing) the test is far more sensitive. Ten patients with disorders of the macula with normal standard white Amsler grid testing were studied with three other Amsler grid tests. Of the 15 involved eyes, 12 had visual field defects present with threshold Amsler grid testing. Tangent screen examination showed defects in 10 of these 12 eyes. The two red grids used were not as sensitive as the threshold grid. Three eyes had metamorphopsia with the white grid which became the site of a visual field defect with threshold testing. Threshold Amsler grid testing is a rapid and sensitive technique for the evaluation of the central 10 degrees of visual field in patients with maculopathies.  相似文献   
93.
Endometriosis and angiogenesis   总被引:2,自引:0,他引:2  
Endometriosis is a common gynecological condition, responsible for significant morbidity and social-economic impact. Although the condition has been recognized for many years, the underlying pathophysiology is poorly understood. In turn, this results in inadequate treatment and high recurrence rates. Various theories try to explain the presence of endometrial tissue outside the uterine cavity. However, none of them can explain all disease locations and appearances, and it is unclear how these fragments establish into endometriotic lesions. New vessel formation has long been recognized as a feature of endometriosis, often clearly visible at laparoscopy. Recent work has focused on identifying the role of vascularization in the pathogenesis of endometriosis, by allowing lesions to establish and grow. In this review the authors outline the basic mechanisms of angiogenesis and vasculogenesis in the human eutopic endometrium, and consider how this data can be applied to endometriotic implants. Furthermore, the authors discuss molecular mechanisms of angiogenesis and vasculogenesis, and how this may be used to therapeutic advantage in the treatment of endometriosis.  相似文献   
94.
95.
96.

Objective

Metronidazole is the drug of choice for the treatment of bacterial vaginosis (BV). However, so far the oral administration has not been clinically compared to the intravaginal application regarding efficacy, side effects and patient satisfaction in a scientific sound fashion.

Study design

Therefore, this randomized, double-blind, placebo-controlled clinical trial was designed to demonstrate non-inferiority of short-term intravaginal (i.vag.) application of metronidazole (2× 1000 mg pessaries 24 h apart) vs. a single oral dose (p.o.) of metronidazole (1 × 2000 mg tablets) in 263 patients with BV (double-dummy design). The follow-up period was 12 weeks. In addition, the number and the type of adverse events induced by the two regimens were compared, assuming better tolerability of the intravaginal application.

Results

Following the diagnosis of BV a total of 129 women (mean age 36.2 years) was orally treated with a single dose of 2 g metronidazole whereas a total of 134 patients (mean age 35.5 years) was treated intravaginally with 1 g metronidazole each day on two consecutive days and included in the per-protocol analysis. Non-inferiority of i.vag. application compared to p.o. administration was statistically significant regarding efficacy: Following intravaginal application the cure rate, assessed on day 8 after starting of the treatment, was 92.5% as compared to 89.9% after oral administration. Nausea was the most common adverse event reported in 10.2% i.vag. vs. 30.4% p.o. of all cases (p < 0.001), abdominal pain in 16.8% i.vag. vs. 31.9% p.o. (p < 0.01), a “metallic taste” in 8.8% i.vag. vs. 17.9% p.o. (p < 0.05). Women treated i.vag. were highly satisfied with the treatment and more content as compared to the women treated p.o. with metronidazole (p < 0.05, intent-to-treat analysis).

Conclusion

In this clinical trial the intravaginal application was as effective as the oral administration of metronidazole in treating BV. However, significantly less adverse events were reported after short-term intravaginal as compared to oral application (p = 0.023) and probably led to a better patient compliance.  相似文献   
97.
98.
99.
Pairs of first molar tooth germs from 17-day rat embryos were cultured in vitro, one member of the pair having additional vitamin A added to the medium on which it was grown. The germs cultured on hyper-A medium were smaller than the control teeth, and lagged in cusp development. The histodifferentiation of the enamel organs was severely affected, but the dental papillae showed less differences. The changes were almost completely reversible up to 7 days of culture.  相似文献   
100.
    
Zusammenfassung An Hand von 51 Wasserproben aus verschiedenen Gegenden Bayerns mit verschiedener geologischer Formation und unterschiedlicher Kropfendemiest?rke wird der Zusammenhang zwischen Fluorgehalt des Trinkwassers und Kropfvorkommen geprüft. Es wird festgestellt, da? zwischen hohem Fluorgehalt des Wassers und starker Kropfendemie keine Parallelit?t besteht. Der h?chste durchschnittliche Fluorgehalt wurde dabei in dem Gebiet gefunden, das in Hinblick auf die Endemiest?rke erst an dritter Stelle steht. Zwei bezüglich der Kropfh?ufigkeit so verschiedene Gegenden wie das Bayerische Diluvium und Alluvium und der Bayerische Jura weisen dieselben Durchschnittswerte auf. Die Befunde vonv. Fellenberg aus der Schweiz, der fand, da? schwaches Auftreten der Kropfendemie stets mit fluorarmem Wasser zusammenf?llt, w?hrend starkes Auftreten sowohl an Orten mit wenig als auch mit solchen mit viel Fluor im Wasser vorkommt, k?nnen nicht best?tigt werden. Die Theorie verschiedener Autoren, die einen urs?chlichen Zusammenhang zwischen Fluorgehalt des Trinkwassers und Kropfentstehung annehmen, ist demnach abzulehnen. Es wird gezeigt, da? der Fluorgehalt des Wassers von der Wasserherkunft abh?ngig ist; Pumpbrunnen enthalten im Durchschnitt mehr Fluor als Quell- und Leitungswasser. Eine endgültige Kl?rung der Frage, ob das Element Fluor und seine Verbindungen die Kropfentstehung beeinflussen, kann durch Wasseruntersuchungen allein nicht herbeigeführt werden. Es wird daher die Untersuchung der Lebensmittel, die nicht nur anorganisches, sondern auch organisch gebundenes Fluor enthalten, gefordert, da organische Fluorverbindungen im K?rper einem andersartigen Resorptionsmechanismus unterliegen als anorganische und die mit der Schilddrüse im Zusammenhang stehenden Stoffwechselvorg?nge viel intensiver zu beeinflussen verm?gen. D 19.  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