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   3761篇
  免费   149篇
  国内免费   65篇
耳鼻咽喉   86篇
儿科学   52篇
妇产科学   83篇
基础医学   599篇
口腔科学   54篇
临床医学   319篇
内科学   852篇
皮肤病学   45篇
神经病学   432篇
特种医学   95篇
外科学   365篇
综合类   45篇
预防医学   199篇
眼科学   56篇
药学   457篇
中国医学   2篇
肿瘤学   234篇
  2022年   42篇
  2021年   86篇
  2020年   31篇
  2019年   59篇
  2018年   83篇
  2017年   49篇
  2016年   43篇
  2015年   60篇
  2014年   98篇
  2013年   138篇
  2012年   175篇
  2011年   217篇
  2010年   123篇
  2009年   126篇
  2008年   158篇
  2007年   188篇
  2006年   195篇
  2005年   197篇
  2004年   172篇
  2003年   163篇
  2002年   161篇
  2001年   145篇
  2000年   130篇
  1999年   112篇
  1998年   54篇
  1997年   30篇
  1996年   37篇
  1995年   34篇
  1994年   22篇
  1993年   13篇
  1992年   41篇
  1991年   55篇
  1990年   63篇
  1989年   65篇
  1988年   60篇
  1987年   74篇
  1986年   49篇
  1985年   65篇
  1984年   33篇
  1983年   30篇
  1982年   21篇
  1981年   14篇
  1980年   13篇
  1979年   33篇
  1978年   13篇
  1977年   14篇
  1974年   28篇
  1973年   21篇
  1972年   22篇
  1971年   25篇
排序方式: 共有3975条查询结果,搜索用时 15 毫秒
981.
982.
983.
In the present study we examined the effects of prenatal manganese (Mn) intoxication on [3H]glucose uptake in the brain of rats lesioned as neonates with 6-hydroxydopamine (6-OHDA). MnCl2 ? 4H2O (10,000 ppm) was added to the drinking water of pregnant Wistar rats for the duration of pregnancy. On the day of parturition, Mn was discontinued as an additive to the drinking water. The control group consisted of rats that consumed water without Mn. Three days after birth, rats in both groups (control and Mn) were pretreated with desipramine hydrochloride (20 mg/kg) and pargyline hydrochloride (50 mg/kg) and injected bilaterally icv with one of three doses of 6-OHDAhydrobromide (15 μg, 30 μg or 67 μg base form in saline on each side) or with saline (control). 6-[3H]-Dglucose (500 μCi/kg, ip) was administered to male offspring in adulthood; after 15 min, brain specimens were taken (frontal cortex, hippocampus, striatum, thalamus with hypothalamus, pons and cerebellum) for determination of radioactivity in a liquid scintillation counter. Low dose 6-OHDA (15 μg icv) increased [3H]glucose uptake in all brain regions (p < 0.05) in both control and Mnintoxicated animals. In rats lesioned with a moderate dose of 6-OHDA(30 μg icv), [3H]glucose uptake was unaltered in both control and Mn-exposed rats. High dose 6-OHDA(67 μg icv) reduced [3H]glucose uptake in all brain regions of Mn-exposed rats (except for cerebellum) compared with the saline group (all, p < 0.05). There was no change in regional brain uptake of [3H]glucose in control rats. In conclusion, this study shows that mild neuronal insult (15 μg icv 6-OHDA) increased glucose uptake in the brain while severe damage (concomitant 60 μg icv 6-OHDA and Mn treatment) significantly diminished this process.  相似文献   
984.
985.
Lungenembolie     
In the population the annual incidence of pulmonary embolism amounts to 1.3-2.8 per 1000 at the age of 65-89 years. Mortality reaches about 17% within the first 3 months. Acute pulmonary embolism is characterized by an increase in pulmonary arterial pressure and an impairment of the pulmonary gas exchange. Elevation of the right cardiac pressure up to right heart decompensation may follow. In addition, hypoxemia, hyperventilation, dead space ventilation, right to left shunting, bronchoconstriction, and vasoconstriction may occur. Clinical examination, ECG, laboratory findings such as elevated D-dimer, blood gas analysis, ultrasound examination of the veins of the lower extremities, and transthoracic echocardiography are acutely available diagnostic methods of an emergency department. In addition, extensive diagnostic procedures like pulmonary scintigraphy and pulmonary angiography may be required. The aim is to get a definite diagnosis as quickly as possible to direct therapy. In acute pulmonary embolism with cardiac shock, monitoring and stabilization of the circulatory function as well as an appropriate anticoagulant therapy are essential. In some cases surgery or a local fibrinolytic intervention is indicated.  相似文献   
986.
987.
988.
Introduction  Recreational shooting in indoor firing ranges is very popular in Germany. Lead-containing ammunition is still in use. Therefore we checked the blood lead levels (BLL) from 129 subjects doing several types of shooting disciplines. Methods  In total, BLLs of 129 shooters (nine female) from 11 different shooting ranges with a mean age of 49 years were measured. The blood samples were taken after the volunteers had given written informed consent. Determination of lead was carried out by graphite furnace atomic absorption (GF-AAS) under strict internal and external quality control schemes. Results  While individuals shooting only with airguns (n = 20) showed a median BLL of 33 μg/l (range 18–127 μg/l), those who were also users of .22 lr weapons (n = 15) turned out to have a median of 87 μg/l (range 14–172 μg/l). Shooters of .22 lr and large calibre handguns (9 mm or larger) (n = 51) had median 107 μg/l (range 27–375 μg/l) and those only using large calibre handguns (n = 32) had median 100 μg/l (range 28–326 μg/l). The IPSC-group (n = 11) had the highest median with 192 μg/l (range 32–521 μg/l). Conclusion  Our results show clearly that many shooters have high blood levels; some of them are still exceeding threshold limit values (TLVs) for lead exposed workers. Especially for younger women there is a high potential risk if they become pregnant. So there is a clear need for improving the situation whether by use of lead-free ammunition or by better ventilation systems.  相似文献   
989.
The aminopyrimidine inhibitor AMN107 (Nilotinib) was rationally designed to antagonize the aberrant tyrosine kinase activity of Bcr-Abl-positive cells. We here evaluated, whether AMN107 is also able to induce apoptosis in Bcr-Abl-negative cells of lymphatic origin. The B-cell lines DOHH-2 and WSU-NHL and the T-cell lines Jurkat and HUT78 were incubated with increasing amounts of AMN107 corresponding to clinically achievable dosages. Subsequently, induced molecular changes were assessed by FACS analysis, Western blot, and enzyme activity assays. Although AMN107 exhibited only a minor apoptosis-inducing effect in the T-cell lines, it exerted a considerable, dose-dependent cytotoxicity in the B-cell lines. Using selective caspase-inhibitors, we show that apoptosis in responder cell lines critically relies on activation of caspase-6 and caspase-9. Cell lines sensitive and resistant towards AMN107 can be discriminated by their differential expression of Src-kinases. Although the AMN107-sensitive cell lines DOHH-2 and WSU-NHL exhibited low or no expression of the Src-kinases Lck, phosphorylated Lck, and Yes with a concomitant high expression of Hck, Lyn, and phosphorylated Lyn, the expression pattern of these kinases was inverse in the AMN107-resistant T-cell lines. In conclusion, this is the first report providing evidence that activity of AMN107 is not restricted to Bcr-Abl, c-Kit, or PDGFR-positive cells, but also extends to lymphatic cell lines of B-cell origin.  相似文献   
990.
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