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   168969篇
  免费   7673篇
  国内免费   473篇
耳鼻咽喉   2408篇
儿科学   5429篇
妇产科学   4578篇
基础医学   23290篇
口腔科学   4630篇
临床医学   11325篇
内科学   38647篇
皮肤病学   5479篇
神经病学   13913篇
特种医学   3863篇
外国民族医学   31篇
外科学   21436篇
综合类   876篇
一般理论   40篇
预防医学   17373篇
眼科学   3442篇
药学   12101篇
中国医学   535篇
肿瘤学   7719篇
  2023年   931篇
  2022年   1602篇
  2021年   3712篇
  2020年   1973篇
  2019年   3639篇
  2018年   4948篇
  2017年   3159篇
  2016年   3167篇
  2015年   3494篇
  2014年   4605篇
  2013年   6749篇
  2012年   10152篇
  2011年   10484篇
  2010年   5760篇
  2009年   4977篇
  2008年   8547篇
  2007年   8996篇
  2006年   8787篇
  2005年   8809篇
  2004年   8217篇
  2003年   7656篇
  2002年   7353篇
  2001年   5289篇
  2000年   5452篇
  1999年   4538篇
  1998年   1269篇
  1997年   904篇
  1996年   852篇
  1995年   734篇
  1994年   617篇
  1992年   2263篇
  1991年   2157篇
  1990年   2002篇
  1989年   1769篇
  1988年   1609篇
  1987年   1588篇
  1986年   1470篇
  1985年   1417篇
  1984年   1042篇
  1983年   887篇
  1979年   1010篇
  1978年   670篇
  1975年   676篇
  1974年   887篇
  1973年   855篇
  1972年   743篇
  1971年   696篇
  1970年   748篇
  1969年   709篇
  1968年   671篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
In search of potential drugs for the treatment of estrogen- and androgen-dependent cancer as well as the prophylaxis of metastases, tetralones, tetralins, and dihydronaphthalenes bearing a OCH3 substituent at the benzene nucleus and an imidazol-4-yl, imidazol-1-yl, or 1,2,4-triazol-1-yl substituent in 2-position were synthesized with and without C1-spacer between the rings (compounds 2 – 26 ). The compounds were tested in vitro for inhibition of the three target enzymes P450 arom (human placental microsomes), P450 17 (rat testicular microsomes), and P450 TxA2 (citrated human whole blood). To examine selectivity, some compounds were further tested in vitro for inhibition of P450 18 (bovine adrenal mitochondria), P450 see (bovine adrenal mitochondria) and corticoid formation (aldosterone, corticosterone; ACTH stimulated rat adrenal tissue). In vivo, selected compounds were examined in Sprague Dawley rats regarding P450 TxA2 inhibition, reduction of plasma testosterone concentration, antiuterotrophic activity (inhibition of the uterotrophic activity of androstenedione), reduction of plasma estradiol concentration (pregnant mares' serum gonadotropin-primed rats), and mammary tumor inhibiting activity (dimethylbenzanthracene-induced tumor; pre- and postmenopausal model). In the series of imidazol-4-yl compounds, which represent a novelty in the field of azole inhibitors of steroidogenic P450 enzymes, strong inhibitors of P450 arom and/or P450 17 were found: 7-OCH3-2-(imidazol-4-ylmethylene)-1-tetralone ( 4 ) and 7-OCH3-2-(imidazol-4-ylmethyl)-tetralin ( 12 ) are among the most potent inhibitors of P450 arom in vitro known so far. Compound 4 is a selective inhibitor, whereas 12 shows in addition strong inhibition of P450 17. In contrast to 12 , the 6-OCH3 derivative (compound 11 ) is a selective inhibitor of P450 17, being 50 times more potent than ketoconazole. Some imidazol-1-yl compounds show a marked inhibition of P450 TxA2: 2-(imidazol-1-ylmethyl)-1-tetralone ( 13 ) is a selective inhibitor of P450 TxA2, whereas 7-OCH3-2-(imidazol-1-ylmethyl)-tetralin ( 17 ) as well as 2-(imidazol-1-ylmethyl)-tetralin ( 16 ) and 7-OCH3-2-imidazol-1-yl-3,4-dihydronaphthalene ( 25 ) additionally show strong inhibition of P450 arom and P450 17. Regarding the other steroidogenic P450 enzymes as well as corticosterone formation, the compounds show only little inhibitory activity. Aldosterone formation, however, is inhibited at low concentrations. Nevertheless, 4 and 12 are more selective, i.e. inhibit aldosterone synthesis less than the well known inhibitor of P450 arom fadrozole. The compounds show activity in the aforementioned in vivo tests.  相似文献   
112.
113.
Fifty-one patients with deep-seated soft tissue sarcoma of the extremities and trunk wall were examined with contrast-enhanced CT for presence of nonenhanced tumor areas (CT necrosis). After a median follow-up time of 3 years, 19 of the 41 patients with CT necrosis had developed metastases, compared to none of the 10 patients who had tumors without CT necrosis. Tumors with CT necrosis were larger than tumors without, but in tumors of similar size, absence of CT necrosis was a favorable prognostic sign.  相似文献   
114.
In order to study the possible regressive changes of left ventricular hypertrophy in treated hypertensive patients and to correlate them either with the drugs they received and/or the blood pressure reduction obtained, a long-term (6 years) echocardiographic follow-up study was performed in 61 patients. B and M mode echocardiographic septum and posterior wall thickness and left ventricular mass index were measured yearly and the type of ventricular hypertrophy, asymmetric septal or concentric (symmetric), were compared before and after the follow-up. Sixteen patients received only diuretics; 14, only propranolol, and associated therapy was used in the remaining 31 patients. Average blood pressure was significantly reduced in the whole group of patients, but, individually, 30 of them achieved normal levels for the diastolic (90 mmHg), remaining it over this value in the other, although all of them experienced an average reduction 10 mmHg with therapy. Those patients with concentric hypertrophy at entry showed a significant septal, posterior wall thickness and total ventricular mass reduction during the follow-up, those with initial asymmetric septal hypertrophy, a significant septal thickness and ventricular mass reduction, and those without hypertrophy on admission, showed an average paradoxical increase in septal thickness. We conclude that left ventricular hypertrophy disappeared or decreased in 48% of the patients and that treatment seems to prevent its progression or development in the 43% of all patients. The regressive or favorable changes were significantly more frequent among patients with normal blood pressure after treatment as well as among patients treated only with propranolol in comparison to those treated only with diuretics.  相似文献   
115.
A study of 16 patients who underwent intralbugineous testicular implants during the practice of orchiectomy is presented. In 14 cases of prostatic carcinoma, after bilateral subcapsular orchiectomy intralbugineous prostheses were implanted and in 2 other cases of testicular torsion unilateral prosthesis was implanted. With this new, easily executed technique the size, mobility and testicular sensibility are maintained.  相似文献   
116.
Authors report on arterial injuries in a 2-year material of hand injured. The combination of injuries observed and the methods of treatment are described. Attention is called to the fact, that because of anatomical characteristics of these regions, the diagnosis of arterial injuries is not always easy. Four cases of their own are briefly described in whom the arterial injury could be stated only at the development of complications (pulsating haematoma, false aneurysm, later bleeding). The importance of the primary careful treatment and the significance of the examination of the circulation (Allen's test, Doppler) are stressed.  相似文献   
117.
118.
We report the case of a 32-year-old multipara who presented preeclampsia on the fourth day after childbirth without receiving proper treatment that progressed to eclampsia 4 days later. Pregnancy and delivery had been uneventful. The patient presented proteinuria (30 mg/dl), serum total proteins 5.3 g/dl and serum albumin 3.3 g/dl. Blood pressure was controlled with methyldopa, 500 mg at six-hour intervals by intravenous route. The patient presented hypoxemia secondary to bilateral pleural effusion and aspirative pneumonia requiring mechanical ventilation and invasive hemodynamic monitoring. Treatment with cefotaxime, 1 g at six-hour intervals by intravenous route and clindamycin, 600 mg at six-hour intervals by intravenous route was initiated. Sedation was maintained with thiopental sodium, 3 mg/kg/hour in continuous infusion. At dismission, the patient was completely recovered from her clinical picture and needed no antihypertensive therapy. Physiopathologic features and the aforementioned complications are discussed with particular reference to differential diagnosis.  相似文献   
119.
120.
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