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   378969篇
  免费   24161篇
  国内免费   2810篇
耳鼻咽喉   5188篇
儿科学   8203篇
妇产科学   10077篇
基础医学   53080篇
口腔科学   11785篇
临床医学   30080篇
内科学   78246篇
皮肤病学   8544篇
神经病学   27209篇
特种医学   13911篇
外国民族医学   82篇
外科学   60577篇
综合类   9954篇
现状与发展   1篇
一般理论   64篇
预防医学   17427篇
眼科学   9444篇
药学   30976篇
  1篇
中国医学   2194篇
肿瘤学   28897篇
  2021年   2612篇
  2019年   2725篇
  2018年   4517篇
  2017年   3431篇
  2016年   3515篇
  2015年   4018篇
  2014年   5690篇
  2013年   7370篇
  2012年   10017篇
  2011年   10197篇
  2010年   6187篇
  2009年   5835篇
  2008年   9444篇
  2007年   10278篇
  2006年   10210篇
  2005年   9255篇
  2004年   8769篇
  2003年   8503篇
  2002年   8183篇
  2001年   28240篇
  2000年   28775篇
  1999年   23648篇
  1998年   5163篇
  1997年   4250篇
  1996年   3827篇
  1995年   3481篇
  1994年   3104篇
  1993年   2843篇
  1992年   16050篇
  1991年   14811篇
  1990年   14154篇
  1989年   13961篇
  1988年   12581篇
  1987年   12062篇
  1986年   11101篇
  1985年   10321篇
  1984年   6913篇
  1983年   5600篇
  1982年   2718篇
  1979年   5477篇
  1978年   3347篇
  1977年   2971篇
  1975年   2641篇
  1974年   3064篇
  1973年   2865篇
  1972年   2830篇
  1971年   2773篇
  1970年   2511篇
  1969年   2543篇
  1968年   2250篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In the past 20 years, we experienced 242 myasthenic patients in our hospital. Fifty five cases were administered high doses of adrenocorticosteroid hormone for a long time. Among them, we analysed 39 cases with complete clinical records from admission to the present. We analysed 5 additional cases in whom responses to the therapy somewhat unique in that four cases have not shown any improvement until the drug was reduced to certain dosages, and in the 5th case change of method from alternate-day to every day brought good recovery of the symptoms. As a result, adrenocorticosteroid hormone was effective for 100% of the patients in this series. However, complete remission appeared in the above mentioned 10 patients (26%), after 2-3 years' continuous administration. Prognosis was far better in those who showed shorter durations between the onset of the disease and thymectomy or thymectomy than in those of longer one. In these cases, the maximum daily doses were 60-100 mg in alternate-day administration, and the total amount of prednisolone was 9-15 g in individual cases. Through data of these cases, it is recommended that the maximum dosage is to be continued for as long as 2 to 19 weeks with average 7 weeks.  相似文献   
992.
We treated 5 cases of severe hydronephrosis with balloon dilation. Those hydronephrosis were due to the ureteral stricture with small stone fragments after ESWL (Lithostar). In each case, in situ ESWL had been done on a long-lodged ureteric stone with severe hydronephrosis. And even after the disintegration of stone with ESWL, hydronephrosis remained due to ureteral stricture with small stone fragments. Balloon dilation was done through percutaneous nephrostomy tract in 4 cases and via retrograde transurethral routine in 1 case. Balloon dilation catheter (7 fr. 6 mm diameter 4-10 cm length, Bard Co.) was used. There was no need for stone extraction. After dilation, ureteric stents (8.2/7 fr.) were kept in place for 4-8 weeks. Intravenous urogram was taken on 4-8 weeks after removing ureteric stents. In all of the 5 cases, improvement of hydronephrosis was remarkable. And there was no residual stone fragments in 4 cases. It is concluded that balloon dilation for ureteral stricture with stone fragments after ESWL is very useful. For the valid evaluation of balloon dilation, further experience and longer observation are requisite.  相似文献   
993.
994.
The effect of prostaglandin E1 (PGE1) on platelets is mediated through the PGE1 receptor and the consequent maintenance of the platelet's discoid shape. The effects of PGE1 and dibutyryl cAMP (dbcAMP) on the deformability of human platelets were studied. Deformability tests based upon the micropipette aspiration on the platelets were performed by using pipettes with radii (Rp) of 0.26-0.36 gm. The time course of the extension length (Dp, in μg) of the platelets in response to aspiration with a negative pressure (ΔP) of 5 cm H2 O (ΔP × Rp = 0.15 dynes/cm) was analyzed. PGE1 treatment (0.1 μM) resulted in a decrease of platelet deformability as compared with results obtained for apparently non-activated, control platelets. The deformation index, i.e., Dp/Rp (PGE1 -treated) / Dp/Rp (control), was significantly reduced to 0.90 ± 0.04. DbcAMP treatment also significantly decreased the deformability of platelets and this decrease was dbcAMP dose dependent. In contrast, colchicine- or cytochalasin D-treated platelets increased deformability. PGE1 -treated platelets had a higher [cAMP]i than controls. Platelets treated with PGE1 or dbcAMP showed a reduced [Ca2+]i increment induced by thrombin as compared to non-treated controls. These results indicate that PGE1 and dbcAMP treatment of platelets is accompanied by an enhancement of platelet resistance to deformation. The increased [cAMP]i and low [Ca2+]i after PGE1 treatment may limit the rearrangement of cytoskeleton and thus enhance platelet resistance to deformation.  相似文献   
995.
996.
997.
998.
Buserelin, a luteinizing hormone releasing hormone agonist was administered nasally in doses of 900 micrograms daily to inhibit the ovarian cycle. Of 16 patients recruited, ten completed the treatment. Daily symptoms were measured on the Visual Analogue Scale and Trigg's trend analysis utilized for the analysis. The peak severity of symptoms (ESAmax) and the maximum global scores (Gmax) reduced on buserelin treatment. The minimum global scores (Gmin) and the minimum score for each symptom (ESAmin) increased, suggesting worsening of underlying symptoms. The difference between ESAmax and ESAmin (ESAdelta) and Gmax and Gmin (Gdelta) were calculated to determine the degree of symptom change. The delta scores for symptoms of depression, bloatedness and breast symptoms, and Gdelta were significantly reduced (p less than 0.05) on buserelin, whilst the latter significantly worsened in the follow-up months. Side-effects may limit the place of buserelin in the long-term treatment of premenstrual syndrome, although combination of additional hormonal treatment may facilitate long-term treatment.  相似文献   
999.
A case of Plasmodium falciparum malaria is reported in a 25-year-old pregnant woman with a history of three previous cesarean sections. She developed premature precipitate labor which was complicated by stillbirth, uterine rupture, bladder and vaginal tears necessitating hysterectomy.  相似文献   
1000.
The generation of monoenergetic or quasimonoenergetic x-ray spectra has been accomplished by several methods including the use of K-edge filtration, characteristic radiation, crystal monochromators, and multilayer mirrors. In this paper some practical questions are discussed regarding the possibility of obtaining narrow-band spectra using x-ray reflection in glass capillary optics which have been reported recently in connection with the focusing and generation of parallel x-ray beams. Derivation of formulas for double and triple reflection with and without additional K-edge filtration imply that these methods are superior to the use of filtration alone. It is shown that the double reflection scheme is most sensitive to the angular divergence of the beam emanating from the capillary array used to generate the incident parallel beam. Simulations using three reflections predict output spectra which are relatively insensitive to blurring due to angular divergence. A small amount of K-edge filtration in combination with three reflections provides considerable sharpening of the x-ray spectrum. Aside from the spectral selectivity provided by the capillary array, the reduced divergence of the primary transmission may have advantages for scatter rejection in situations where the air gap between the patient and detector is increased by an amount consistent with the resolution requirements of the application. In parallel beam situations, the use of capillary arrays between the patient and detector may also be useful for the rejection of divergent scattered radiation.  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