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   3233篇
  免费   235篇
  国内免费   31篇
耳鼻咽喉   74篇
儿科学   61篇
妇产科学   77篇
基础医学   492篇
口腔科学   45篇
临床医学   283篇
内科学   759篇
皮肤病学   44篇
神经病学   248篇
特种医学   214篇
外科学   426篇
综合类   104篇
一般理论   2篇
预防医学   150篇
眼科学   26篇
药学   304篇
中国医学   8篇
肿瘤学   182篇
  2023年   21篇
  2022年   57篇
  2021年   107篇
  2020年   49篇
  2019年   63篇
  2018年   86篇
  2017年   67篇
  2016年   72篇
  2015年   76篇
  2014年   115篇
  2013年   170篇
  2012年   260篇
  2011年   283篇
  2010年   157篇
  2009年   115篇
  2008年   206篇
  2007年   212篇
  2006年   213篇
  2005年   164篇
  2004年   179篇
  2003年   154篇
  2002年   144篇
  2001年   35篇
  2000年   37篇
  1999年   37篇
  1998年   22篇
  1997年   27篇
  1996年   22篇
  1995年   19篇
  1994年   8篇
  1993年   9篇
  1992年   24篇
  1991年   22篇
  1990年   16篇
  1989年   16篇
  1988年   14篇
  1987年   17篇
  1986年   16篇
  1985年   27篇
  1984年   13篇
  1983年   17篇
  1982年   11篇
  1981年   10篇
  1980年   13篇
  1978年   8篇
  1976年   9篇
  1975年   12篇
  1974年   9篇
  1973年   10篇
  1972年   7篇
排序方式: 共有3499条查询结果,搜索用时 15 毫秒
991.
This prospective randomized study compared the effectiveness of a flexible single-dose gonadotrophin-releasing hormone (GnRH) antagonist (cetrorelix) and a single-dose long GnRH agonist (goserelin) protocol for ovarian stimulation in IVF/intracytoplasmic sperm injection (ICSI) cycles. All patients from the waiting list were successively included in the study, pre-programmed with an oral contraceptive, and randomized into goserelin and cetrorelix groups. Depending on the date on which their menstrual period started, patients took oral contraceptives for one or two cycles. Ultimately, 236 patients in the first group received a single dose of depot preparation of goserelin and 224 patients received a single 3 mg dose of cetrorelix in the late follicular phase, when the mean follicle diameter exceeded 12 mm. The mean number of ampoules of FSH and the duration of stimulation was statistically significantly lower in the cetrorelix group than in the goserelin group (25.9 versus 34.5, and 9.6 versus 12.2 days, P < 0.01). The mean number of oocytes retrieved was similar (6.7 +/- 4.5 versus 7.2 +/- 4.6, NS). Similar results were observed in fertilization rates, blastulation rates and blastocyst transfer rates in both groups. Clinical pregnancy and delivery rates per cycle were higher in the goserelin group (34.3 and 30.1%) than in the cetrorelix group (31.9 and 28.3%), but the differences were not statistically significant. The flexible single-dose GnRH antagonist protocol is an advantageous alternative to the long GnRH agonist protocol, with similar efficacy, shorter duration, a significant reduction in the number of FSH ampoules used and without the menopause-like effects of the GnRH antagonist.  相似文献   
992.

Editorial Commentary

Rapid and accurate LV surface generation from 3D echocardiography by a catalog based method  相似文献   
993.
BACKGROUND AND OBJECTIVES: Medial branch blocks are an important tool for the diagnosis of facet joint arthropathy. The most commonly used technique involves multiple needle placements, one for each nerve blocked. This multiple needle technique may require a large amount of local anesthetic for anesthetizing the skin, thereby increasing the rate of false-positive blocks. TECHNIQUE: Diagnostic lumbar medial branch blocks are usually performed using multiple needles, one for each branch. The authors describe a different technique using a single needle for all levels. Initially, the needle is directed toward the medial branch located at the level of the affected facet joint in the antero-posterior view. After anesthetizing this nerve with local anesthetic, the same needle is withdrawn to the skin with the tip still in the subcutaneous tissue and repositioned to block the medial branch above, and thereafter below, while continuing to use only the antero-posterior view, thereby using only one entry site. CONCLUSIONS: When performed correctly, the single needle technique provides accuracy similar to the more conventional multiple needle approach during the performance of diagnostic facet joint nerve blocks. Because only one skin entry point is needed, however, this technique may afford several advantages over the multiple needle approach. These may include less patient discomfort, less time required and less radiation exposure since only one C-arm position is used, a smaller volume of local anesthetic, and possibly a lower incidence of false-positive blocks.  相似文献   
994.
995.
Non-Hodgkin lymphomas (NHL) often show up in an extranodal pattern, especially in the head and neck. Intraoral locations are much less frequent, particularly when they are single. This, in turn, can lead to a prolonged diagnosis and even to inadequate treatment. Different patients with initial extranodal location of NHL which were not previously diagnosed and in which it was manifested only intraorally are presented in this paper. These cases are presented together with the additional examinations used for the early diagnosis and with the corresponding clinical pictures, as well as with the overview of other cases from the available literature.  相似文献   
996.
997.
The aim of the study is to evaluate the intensity of the operative trauma during laparoscopic and open cholecystectomy measured by hormonal (cortisol level) and metabolic (blood sugar level) response. Prospective randomized study was conducted in seventy patients with cholelithiasis. They were divided in two groups: thirty five underwent laparoscopic cholecystectomy and thirty five underwent open cholecystectomy (control group). Mean cortisol concentration and glucose concentration were measured preoperatively and postoperatively after 2, 4, 8, 12, 24 and 48 hours. The examined groups were comparable in age and sex. Preoperative plasma cortisol concentration was within normal range in both groups. Postoperatively plasma cortisol level increased in the laparoscopically operated group, and peak level occurred eight hours after surgery (692.6 +/- 27.2 nmol/L). Peak plasma cortisol level in control group developed 8 hours postoperatively (841.1 +/- 33.2 nmol/L). The mean cortisol concentration was significantly higher (p < 0.05) following open procedure between fourth and 48th postoperative hour. Mean plasma glucose concentrations after laparoscopic and open cholecystectomy were significantly higher (p < 0.05) than preoperative values. The mean glucose concentration during the initial 24 hours was significantly higher (p < 0.05) following open cholecystectomy.  相似文献   
998.
Cluff R  Mehio AK  Cohen SP  Chang Y  Sang CN  Stojanovic MP 《Anesthesia and analgesia》2002,95(2):403-8, table of contents
Although epidural steroid injections (ESIs) are a common treatment for chronic pain conditions, it is not clear whether there is consensus on their technical aspects. The current literature suggests that variations in technical aspects may affect ESI outcomes. The goal of the survey was to help establish a standard frame of reference for the performance of ESIs. We analyzed survey results from 68 academic anesthesia programs and 28 private practices in the United States. The main finding in this survey is that there is no clear-cut consensus as to the ideal method to perform ESI. There is a wide variation among individual practices in almost every technical aspect of ESI. Private practices use significantly more fluoroscopy than academic centers. The large difference was found in the cervical region where 73% of private practices and only 39% of academic institutions polled perform the ESIs with fluoroscopic guidance (P = 0.005). A similar discrepancy was found in approaches to the epidural space after laminectomy where 61% of private practices, but only 15% of academic centers, use the transforaminal approach. The study results indicate that there is no consensus, and that there is a wide variation in current practices. IMPLICATIONS: A national survey of practices performing epidural steroid injections was conducted. The purpose was to establish whether consensus exists on technical aspects of this procedure. The study results indicate that there is no consensus, and that there is a wide variation in current practices.  相似文献   
999.
1000.
BACKGROUND: Dialysis efficiency has a great influence on the outcome of patients. Few data are available on the removal of solutes with molecular weights higher than urea and creatinine. The aim of our study was to assess the transport and the removal of substances with molecular weights up to 15 kD and to evaluate the contribution of residual renal function in peritoneal dialysis (PD) children. METHODS: Seventeen patients of 12 +/- 4 years undergoing automated PD were studied. Ten patients had 563 +/- 355 mL/day of urine output, and 7 were anuric. During a standardized nightly intermittent PD (NIPD) session, a single-injection inulin clearance was performed. Urea, creatinine, inulin (measured by HPLC), cystatin C and beta2-microglobulin (beta2m) were measured in blood, urine and dialysate. Clearances (L/week/1.73 m2) and weekly solute removal index (SRI) were calculated for all the solutes; weekly Kt/V was calculated for urea. RESULTS: In non-anuric versus anuric patients the total clearances were: urea 82.6 +/- 18.3 versus 71.3 +/- 26.4; creatinine 82.7 +/- 28.6 versus 47.8 +/- 18.8; inulin 42.8 +/- 11.3 versus 32.8 +/- 20.4; beta2m 14.2 +/- 13.8 versus 9.2 +/- 8.3; cystatin C 20.2 +/- 9.4 versus 9.7 +/- 4.8. In the patients with residual diuresis, the urea was removed mainly by PD (69.2%), while inulin, beta2m and cystatin C were removed by renal clearance (64.0%, 79.5% and 62.8%, respectively). Total, peritoneal and renal weekly Kt/V values in the subjects with residual renal function, were 2.86 +/- 0.70, 1.99 +/- 0.40 and 0.87 +/- 0.43, respectively. Peritoneal weekly Kt/V in the anuric patients was 2.36 +/- 0.85; total weekly Kt/V in the total group was 2.65 +/- 0.78. Weekly SRIs in non-anuric versus anuric patients were: urea 2.56 +/- 0.58 versus 2.09 +/- 0.74; creatinine 2.66 +/- 0.73 versus 1.46 +/- 0.56; inulin 2.36 +/- 0.92 versus 1.64 +/- 1.60; beta2m 1.26 +/- 1.10 versus 1.20 +/- 1.90; cystatin C 1.72 +/- 0.83 versus 1.58 +/- 1.62. CONCLUSIONS: Solutes removed during PD tend to decrease following an increase in molecular weight of the substance. Since anuric patients are at higher risk of middle molecule and small protein accumulation, more attention should be paid to the removal of middle molecules. Further studies should be undertaken to evaluate whether removing them has a clinical impact and to determine their threshold levels.  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