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   227098篇
  免费   9671篇
  国内免费   568篇
耳鼻咽喉   2983篇
儿科学   6891篇
妇产科学   5677篇
基础医学   32478篇
口腔科学   7306篇
临床医学   14322篇
内科学   50844篇
皮肤病学   6936篇
神经病学   18462篇
特种医学   5879篇
外国民族医学   30篇
外科学   27133篇
综合类   1176篇
一般理论   38篇
预防医学   24571篇
眼科学   5316篇
药学   16907篇
中国医学   864篇
肿瘤学   9524篇
  2023年   1155篇
  2022年   1686篇
  2021年   4290篇
  2020年   2371篇
  2019年   4371篇
  2018年   6348篇
  2017年   4055篇
  2016年   4169篇
  2015年   4569篇
  2014年   5782篇
  2013年   8524篇
  2012年   13440篇
  2011年   14017篇
  2010年   7441篇
  2009年   6167篇
  2008年   11587篇
  2007年   12251篇
  2006年   11845篇
  2005年   11554篇
  2004年   10670篇
  2003年   9940篇
  2002年   9567篇
  2001年   6847篇
  2000年   7384篇
  1999年   5935篇
  1998年   1556篇
  1997年   1110篇
  1996年   1045篇
  1992年   3111篇
  1991年   2896篇
  1990年   2844篇
  1989年   2498篇
  1988年   2312篇
  1987年   2162篇
  1986年   2168篇
  1985年   2013篇
  1984年   1486篇
  1983年   1293篇
  1979年   1594篇
  1978年   1075篇
  1975年   1162篇
  1974年   1426篇
  1973年   1461篇
  1972年   1374篇
  1971年   1322篇
  1970年   1263篇
  1969年   1324篇
  1968年   1306篇
  1967年   1173篇
  1966年   1068篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
A series of 5-aminomethinimino-3-methyl-4-isoxazolecarboxylic acid phenylamides 4 has been prepared by condensation of 5-amino-3-methyl-4-isoxazolecarboxylic acid phenylamides 1 with trichloroacetic aldehyde. Alcoholysis of trichloro derivatives 2 gave 5-alkoxymethine derivatives 3 which, on reaction with an appropriate amine, formed the corresponding compounds 4 . The compounds obtained were evaluated for their immunological activity. The properties of three compounds, described in this report, permitted inhibition of the immune response in all possible ways: diminishing both types of immune response ( 4d ), humoral immune response ( 4a ), or cellular immune response ( 4c ). Preparation 4d is comparable in its effectiveness to CsA, so it may be potentially used as an agent for prolongation of the function of transplanted organs. Two other compounds may potentially be used in cases where only one type the immune response is required for combating pathogen invasion.  相似文献   
82.
A total of 186 blood samples from 24 HIV-1 seropositive hemophiliac patients, monitored every four months for 29 months, were investigated for the presence of viral antigen in plasma. In addition, peripheral blood mononuclear cells (PBMC) were cultured for HIV-1, using normal PBMC as a target for replication. Antigenemia was detected in 51 % of the patients and from PBMC in 87.5 % of the patients. The incidence of HIV isolation in asymptomatic patients (42.8 %) was similar to that found in symptomatic patients (51.4 %). Patients with opportunistic infections had a higher incidence of lymphocytic viremia (p<0.05). Plasma viremia was closely associated (p<0.05) with low CD4+ counts and infection progression. The persistence of antigenemia was also a marker of a poor clinical course. In treated patients, plasma viremia was the marker that better correlated with the clinical course, and it did not appear during the first nine months of therapy. Zidovudine doses of >500 mg/day significantly lowered the appearance of antigenemia and lymphocytic viremia (p<0.05).  相似文献   
83.
84.
A comparison of the results of 169 cholecystectomies with the use of a laser scalpel and 160--conventional methods was carried out. The CO2-laser was used for exposure of the gallbladder and coagulation of tissue of the liver in the region of its bed. Hemo- and cholestasis in all the cases was reliable, and due to this fact in 27% of the patients, the subhepatic recess was not drained. The incidence of complications after the elective cholecystectomy reduced by 11%, after the emergency one--by 9%, the lethality reduced considerably.  相似文献   
85.
A series of N-(phosphonoacetyl)-dipeptide derivatives was synthesized for pharmacological testing as antihypertensive compounds. Several of these compounds demonstrated a moderate antihypertensive effect in Wistar spontaneous hypertensive rats (SHR) with p.o. dosing. ACE inhibition by the compounds was studied using ACE from rat plasma and lung. Inhibitors containing esterified C-termini are pro-drugs and showed activity only for plasma ACE.  相似文献   
86.
Authors describe a case of isolated posttraumatic neuropraxy of the musculocutaneous nerve. With the presentation of this very rare case attention is called, based on literary date, to the fact that the above injury can be mixed with the distal tendon rupture of the biceps.  相似文献   
87.
88.
This research presents reports of cases where a biocompatible and alloplastic biomaterial—Bioplastique—was used, associated with conventional plastic surgery or as a complement to it, with the aim of achieving a better final aesthetic result. Four cases are presented where Bioplastique was used in association with rhytidoplasty, rhinoplasty, and other surgical techniques. This material has shown itself to be appropriate to complement surgery; achieving a final result which would not be possible without any resort to a complement or any other hard procedure by the surgeon and is not more traumatic for the patient.  相似文献   
89.
Alcohol consumption during pregnancy is teratogenic and induces severe alterations in hepatocytes. In the hepatocyte peroxisomal system, ethanol is converted in the presence of H2O2 to acetaldehyde and water. Therefore, peroxisomal catalase also acts as an antioxidant defence mechanism by removing H2O2 and preventing the formation of hydroxyl radicals in the cell. Alterations in peroxisomal catalase after pre- and pre+postnatal alcohol exposure were investigated in the rat. The effect of pre- and postnatal exposure to ethanol on hepatocyte subpopulations was analysed in isolated hepatocytes originating from periportal, intermediate and perivenous zones. Analysis of catalase revealed that the total activity and content of this enzyme were higher in 12-day-old cells than in cells from newborns and that this increment was more pronounced in treated cells. In controls, the amount of peroxisomal catalase increased mainly in periportal cells, whereas alcohol exposure induced a significant increase in the catalase of perivenous hepatocytes. We conclude that pre- and postnatal alcohol exposure mainly affects the perivenous hepatocyte peroxisomes and that the increase in peroxisomal catalase could constitute a defence mechanism against free radical generation induced by alcohol exposure during the perinatal period.  相似文献   
90.
A study of 52 middle-aged males with essential hypertension, unaccompanied by cardiovascular disorders, is reported. The patients were divided into 2 groups with respect to the type of treatment they received: 30 patients on beta-adrenoblockers and 22 patients on methyldopa. The patients were treated continuously for 2 years under one-dimensional echocardiographic control. The greatest drop in arterial blood pressure and ventricular septum thickness was seen within the first 6 months of treatment, while posterior-wall hypertrophy disappeared altogether. Although there was no further drop in blood pressure after 6 months, the thickness of the ventricular septum remained reduced for at least 2 years. Regression of left-ventricular hypertrophy was not accompanied with any deterioration of left-ventricular performance, nor was it related to additional use of vasodilators.  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