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   931956篇
  免费   66318篇
  国内免费   1343篇
耳鼻咽喉   12959篇
儿科学   24358篇
妇产科学   23232篇
基础医学   132908篇
口腔科学   28302篇
临床医学   80539篇
内科学   183267篇
皮肤病学   19227篇
神经病学   72181篇
特种医学   36799篇
外国民族医学   79篇
外科学   152101篇
综合类   18042篇
现状与发展   1篇
一般理论   234篇
预防医学   61737篇
眼科学   21307篇
药学   72525篇
  3篇
中国医学   2162篇
肿瘤学   57654篇
  2018年   8963篇
  2017年   7029篇
  2016年   7762篇
  2015年   8862篇
  2014年   11985篇
  2013年   17502篇
  2012年   24086篇
  2011年   25035篇
  2010年   14805篇
  2009年   14265篇
  2008年   24604篇
  2007年   25695篇
  2006年   26485篇
  2005年   25430篇
  2004年   24560篇
  2003年   23607篇
  2002年   23153篇
  2001年   54724篇
  2000年   56545篇
  1999年   46950篇
  1998年   10740篇
  1997年   9467篇
  1996年   9597篇
  1995年   8929篇
  1994年   8280篇
  1993年   7594篇
  1992年   35493篇
  1991年   33912篇
  1990年   32735篇
  1989年   31872篇
  1988年   28993篇
  1987年   28251篇
  1986年   26289篇
  1985年   25145篇
  1984年   17835篇
  1983年   15143篇
  1982年   7798篇
  1981年   6771篇
  1979年   15784篇
  1978年   10599篇
  1977年   9052篇
  1976年   7872篇
  1975年   8628篇
  1974年   10469篇
  1973年   9859篇
  1972年   9357篇
  1971年   8852篇
  1970年   8426篇
  1969年   7923篇
  1968年   7200篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Estramustine phosphate disodium (Estracyt) was used in the treatment of 38 patients with prostatic carcinoma for at least 1 year. Of these patients 37 patients were treated with Estracyt as primary treatment and 1 patient had been treated with another antiandrogenic therapy before the Estracyt treatment. Estracyt was given orally in a dose of 560 mg/day in divided oral doses. The clinical evaluation was done for the change of PAP, the relapse rate, the survival rate and the side effect. Among 22 cases which had shown abnormally high PAP values before the treatment started, the values decreased or normalized in 21 cases (95.5%) in the first year of administration of Estracyt. In 6 cases, however, the values increased again in the second year or later. Relapse was observed in 10 (26.3%) out of 38 cases. Relapse rate was 2.6%, 51.7%, and 51.7%, at the first, third, and fifth year, respectively. Survival rate was 97.4% at the first year, 88.5% at the third year, and 68.8% at the fifth year for the follow-up study. Side effects were observed in 14 (36.8%) out of 38 cases. The main side effect was gynecomastia. Gastro-intestinal disturbance and edema were also observed. However, there were only 2 cases (5.2%) in which administration of Estracyt had to be discontinued.  相似文献   
992.
It is well known that primary hyperparathyroidism is often associated with peptic ulcer. The purpose of this study is to confirm the relationship between the gastrin-levels before and after parathyroidectomy in fourteen patients with primary hyperparathyroidism, and to determine the localization of gastrin in the surgically resected parathyroid tumor. The results obtained were as follows: 1) Three patients had peptic ulcer (gastric ulcer and duodenal ulcer), the incidence being 21%. 2) The basal serum gastrin levels were 123.0% +/- 68.1 pg/ml before operation and decreased to 90.2 +/- 44.5 pg/ml after operation. In the 3 patients with slightly elevated gastrin levels, the mean level before operation was 209.1 +/- 61.2 pg/ml. The gastrin level decreased to 116.4 +/- 62.0 pg/ml after operation. 3) Gastrin immunoreactivity was detected in 10 out of 14 tumors and its localization was at the periphery of tumor cells. From these results, we conclude that extragastric gastrin secretion from parathyroid tumors may be one of the cause of peptic ulcer in patients with primary hyperparathyroidism.  相似文献   
993.
Effects of adrenergic alpha-1-blocking agent, prazosin, in the treatment of detrusor external-sphincter dyssynergia (DSD) were evaluated in both experimental and clinical aspects. Experimentally, in the urethral pressure profile in dogs, the maximum urethral closing pressure was depressed after intravenous injection of 1 mg prazosin. When experimental DSD was obtained in dogs by stimulating electrically the unilateral 2nd sacral root, intra-venous injection of 1 mg prazosin inhibited contraction of the external urethral sphincter. Clinically, 74 patients with DSD based on neurogenic bladder from cerebral vascular attack (CVA) (13 cases) and spinal cord injury (61 cases) were retrospectively surveyed in terms of therapeutical effects of prazosin for DSD. Spinal cord injury was subdivided to 4 groups for clinical evaluation; cervical cord injury (C) with complete paralysis, thoracic cord injury (Th) with complete paralysis, lumbar cord injury (L) with complete paralysis and spinal cord injury with incomplete paralysis. Patients with CVA and spinal cord injury with incomplete paralysis showed good response rates in subjective improvement, 69% and 60% respectively. However, those with spinal cord injury with complete paralysis showed a poor response (28% for C, 23% for Th and 14% for L). The amount of residual urine significantly decreased after treatment, in all the groups except that of lumbar cord injury with complete paralysis. In all the groups, however, even after the drug treatment the amount of residual urine ranged from 80 to 170 ml and the rates of needing clean intermittent catheterization unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
994.
We investigated effects of total body hyperthermia (TBH) on endocrine and hemodynamic responses. A total of five treatments were performed in five patients with gastric cancer under neuroleptanesthesia with morphine followed by 0.2 to 0.4% enflurane. TBH was extracorporeally induced with veno-venous shunt incorporating with heat exchanger to keep their temperature between 41.5 degrees C and 42.0 degrees C for three hours. The patients were administered angiotensin to maintain tumor blood flow. Lactated Ringer's solution was administered at the rate of 10 to 15 ml.kg-1.hr-1 for five hours. Plasma cortisol levels decreased significantly to about one third of the control value after heating and the levels recovered to the control value after cooling. Plasma norepinephrine level increased significantly to about 7 to 9 times the control value following TBH, but this hormonal response was insufficient to reveal marked direct hemodynamic effects. The magnitude of fall in SVR was more significant in spite of the administration of angiotensin. Cardiac index increased significantly to about 2.0 to 2.6 fold of control value, but mean arterial blood pressure (MAP) decreased significantly to about two thirds to four fifths of the control value. Morphine relieved the hormonal response in ACTH and cortisol strongly, but morphine suppressed hemodynamics by decreasing SVR. Neither norepinephrine released from sympathetic nerve endings nor even 50 to 200 ng.kg-1.min-1 of angiotensin administered failed to restore SVR or MAP during hyperthermia.  相似文献   
995.
The gentamicin-containing collagen sponge is a new product intended for local application in bone and soft-tissue infections. The release of gentamicin from the collagen sponges was compared in vitro to that from polymethyl-methacrylate (PMMA) beads. A static and kinetic experimental design was used. In the static model, pieces of collagen sponge or PMMA beads were added to 20 mL of distilled water, and during the following hours the gentamicin concentrations in the water were repeatedly measured. This simple model was extended to the kinetic model as the released gentamicin was removed from the water exponentially by means of an infusion-withdrawal pump. The gentamicin was released from the carrier substances with increasing half lives. During the first 4 hours, the half life increased from 0.2 to 1.5 hours for the collagen sponge and from 3 to 78 hours for the PMMA beads. After 1.5 hours, 95 percent of the gentamicin was released from the sponges, whereas only 8 percent was released from the beads.  相似文献   
996.
Using high resolution ultrasonography (US), diagnostic accuracy of thrombi in each venous segment of lower limbs and qualitative evaluation of thrombi in deep vein thrombosis (DVT) were investigated. The subjects were 106 lower limbs in 81 patients. The thrombi in common femoral vein (CFV), were diagnosed by compression technique and, were qualitatively analysed by echogenicity and consistency. Venography was performed in 18 limbs and histologic tests of thrombi were made in 6 limbs. The total accuracy of US was 100% for diagnosis of DVT, but was 83% for diagnosis of its extent. The total accuracy of US in each segment was greater than 90%, but the sensitivity of iliac veins was less than 90%. The thrombi in CFV were divided into 3 types and 8 sub-types. Type A was homogenous, type B was heterogenous, and type C was contracted echo. The types of us were consistent with results of histologic tests. We concluded that high resolution US is available for screening test for diagnosis of DVT and that qualitative evaluation of thrombi by US is a useful clinical test for selection of more adequate treatments.  相似文献   
997.
Effects of sevoflurane at various anesthetic levels on renal sympathetic nerve activity (RSNA), blood pressure and heart rate were studied in rats. Changes of these parameters produced reflexly by noxious cutaneous stimulation and effects of baroreceptor on them were also studied. Under the resting condition by increasing inspired sevoflurane concentration decreased blood pressure and heart rate dose-dependently, whereas, RSNA was unchanged. But, without the baroreceptor function, RSNA decreased and the change paralleled with changes of blood pressure and heart rate. When noxious stimulation was applied on a hindpaw by pinching, blood pressure, heart rate and RSNA all increased at sevoflurane 2.1%. The responses of these parameters were attenuated at 3.1% and almost disappeared at 4.2% of sevoflurane. However, without the baroreceptor function, RSNA increased even at 3.2 and 4.2% as at 2.1% of sevoflurane. It is suggested that under sevoflurane anesthesia, baroreceptor system has strong influences on RSNA even under sevoflurane 4.2% (2MAC).  相似文献   
998.
Nonocclusive mesenteric ischemia (NOMI) is a disorder with an extremely high mortality. Salvage of affected patients requires early recognition and aggressive intervention to prevent intestinal gangrene. Dialysis patients represent a group at particularly high risk for this condition. Clinicians should develop a high index of suspicion for NOMI in dialysis patients to lessen the risk of death. A high interventional posture must be maintained due to the notoriously unreliable signs and symptoms of this disorder.  相似文献   
999.
Peritoneal macrophages (PM) perform first-line defense activity against peritonitis, the most important complication in continuous ambulatory peritoneal dialysis (CAPD) therapy. Our longitudinal study has compared the PM function in 20 uremic patients during periods free of peritonitis since they started CAPD therapy in January 1987. The results showed that at the initiation of CAPD, there was a higher bactericidal activity, phagocytosis index, H2O2 production and interleukin-1 (IL-1), gamma-interferon (IFN-gamma) and tumor necrosis factor (TNF) production ability and MHC expression. As time went on, these progressively decreased, and by 9 months after CAPD therapy had started they were significantly lower than at the beginning. During the 1.5-year follow-up period, there was a significantly increased peritonitis rate in the period 6 months after the beginning of CAPD than in the period before the 6th month (88.3 vs. 11.7% respectively; p less than 0.001). These results indicate that PM of new CAPD patients have a more active function than those of established patients. The established patients had a greater risk of peritonitis. A comparison of the immunological profiles of PM from patients who had a peritonitis history shows that phagocytosis index, bactericidal activity and IL-1 and TNF production of PM were significantly decreased during the period free of peritonitis. This result suggests that these parameters may serve as an indicator in developing peritonitis.  相似文献   
1000.
To evaluate the effect of UFT, a mixture of ftorafur and uracil in a ratio of 1:4, in preventing postoperative recurrence of bladder cancer, we performed a randomized controlled study with a non-medication group as control. UFT was given orally 400 mg a day for 6 months. Of 111 patients, 56 were given UFT and 55 were followed up without any medication. The non-recurrence rate in the group treated with UFT was 62.8% after 1 year and 36.3% after 2 years of follow up, and that of the control group was 45.7% and 39.5%, respectively. The rate of non-recurrence in the UFT group was significantly higher (p less than 0.05) than that of the control group during the period of follow up for 2 years. The incidence of side effects was 6.8% in UFT patients. These results indicate the clinical usefulness of prophylactic administration of UFT for bladder cancer patients.  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