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   6075篇
  免费   402篇
  国内免费   37篇
耳鼻咽喉   63篇
儿科学   92篇
妇产科学   149篇
基础医学   785篇
口腔科学   61篇
临床医学   678篇
内科学   1431篇
皮肤病学   75篇
神经病学   538篇
特种医学   240篇
外科学   997篇
综合类   39篇
预防医学   317篇
眼科学   113篇
药学   384篇
中国医学   5篇
肿瘤学   547篇
  2024年   9篇
  2023年   59篇
  2022年   83篇
  2021年   234篇
  2020年   163篇
  2019年   220篇
  2018年   262篇
  2017年   169篇
  2016年   181篇
  2015年   161篇
  2014年   251篇
  2013年   328篇
  2012年   491篇
  2011年   401篇
  2010年   246篇
  2009年   235篇
  2008年   364篇
  2007年   366篇
  2006年   359篇
  2005年   339篇
  2004年   280篇
  2003年   259篇
  2002年   261篇
  2001年   71篇
  2000年   61篇
  1999年   54篇
  1998年   59篇
  1997年   50篇
  1996年   49篇
  1995年   40篇
  1994年   27篇
  1993年   15篇
  1992年   28篇
  1991年   32篇
  1990年   30篇
  1989年   30篇
  1988年   24篇
  1987年   22篇
  1986年   21篇
  1985年   16篇
  1984年   11篇
  1983年   9篇
  1982年   7篇
  1981年   10篇
  1976年   10篇
  1974年   7篇
  1973年   7篇
  1972年   12篇
  1970年   11篇
  1969年   9篇
排序方式: 共有6514条查询结果,搜索用时 15 毫秒
61.
UTERINE DISORDERS: Because they can prevent implantation, anomalies within the uterine cavity play an important role in fertility. The uterine disorders most often observed during hysteroscopy and implicated in infertility are adhesions, septa, polyps, submucous myomas, adenomyosis, endometritis, anomalies of the cervical canal, and lesions of the uterotubal junction. EXPLORATIONS: Hysterosalpingography can be used to evaluate tubal permeability but provides inadequate information about the uterine cavity (numerous false-positives and false-negatives). Pelvic ultrasound is especially helpful for diagnosing interstitial anomalies in the uterus. HYSTEROSCOPY: Diagnostic hysteroscopy also has a place in infertility investigations, for it allows direct visualization of the uterine cavity, the endometrial mucus (endometritis, adenomyosis), and the cervical canal. The examination is practiced on a out-patient basis, without anesthesia, using appropriate small-caliber instruments and irrigation with physiological saline. Surgical hysteroscopy is used to treat these anomalies. Patients receive general anesthesia. A high-frequency, low-voltage electric current is used, and glycine for irrigation. This procedure allows resection of submucous myomas and polyps and of septa and adhesions. Some groups use laser beams and irrigation by physiological saline for these treatments. Coagulation of a superficial focal spot of adenomyosis is not useful in infertility therapy. RESULTS: As assessed by the percentage of patients with each indication who subsequently became pregnant, the results of surgical hysteroscopy have been satisfactory: 62 per cent (%) of cases after myomectomy, 66% after section of uterine septa, and 61% after treatment of complicated adhesions. A new exploration of the uterine cavity will be necessary sometime after the surgery to verify the absence of any iatrogenic disorders (adhesions, myomatous fragments).  相似文献   
62.
This study was undertaken to determine whether a pulse protein feeding pattern was more efficient than a spread pattern to improve protein anabolism in young women as was already shown in elderly women. After a 15-d adaptive period [1.2 g protein/(kg fat-free mass. d)], 16 young women (age 26 +/- 1 y) were given a 14-d diet providing 1.7 g protein/(kg fat-free mass. d), using either a pulse pattern (protein consumed mainly in one meal, n = 8), or a spread pattern (spreading daily protein intake over four meals, n = 8). Nitrogen balance was determined at the end of both the 15-d adaptive and the 14-d experimental periods. Whole-body protein turnover was determined at the end of the 14-d experimental period using [(15)N]glycine as an oral tracer. Nitrogen balance was 17 +/- 5 mg N/(kg fat-free mass. d) during the adaptive period. It was higher during the experimental period, but not significantly different in the women fed the spread or the pulse patterns [59 +/- 12 and 36 +/- 8 mg N/(kg fat-free mass. d) respectively]. No significant effects of the protein feeding pattern were detected on either whole-body protein turnover [5.5 +/- 0.2 vs. 6.1 +/- 0.3 g protein/(kg fat-free mass. d) for spread and pulse pattern, respectively] or whole-body protein synthesis and protein breakdown. Thus, in young women, these protein feeding patterns did not have significantly different effects on protein retention.  相似文献   
63.

Introduction  

It has been well documented that the pineal hormone, melatonin, which plays a major role in the control of reproduction in mammals, also plays a role in the incidence and growth of breast and mammary cancer. The curative effect of melatonin on the growth of dimethylbenz [a]anthracene-induced (DMBA-induced) mammary adenocarcinoma (ADK) has been previously well documented in the female Sprague-Dawley rat. However, the preventive effect of melatonin in limiting the frequency of cancer initiation has not been well documented.  相似文献   
64.
65.
66.
Background: The COVID-19 pandemic has put enormous pressure on hospital resources, and has affected all aspects of patient care. As operative volumes decrease, cancer surgeries must be triaged and prioritized with careful thought and attention to ensure maximal benefit for the maximum number of patients. Peritoneal malignancies present a unique challenge, as surgical management can be resource intensive, but patients have limited non-surgical treatment options. This review summarizes current data on outcomes and resource utilization to help inform decision-making and case prioritization in times of constrained health care resources. Methods: A rapid literature review was performed, examining surgical and non-surgical outcomes data for peritoneal malignancies. Narrative data synthesis was cross-referenced with relevant societal guidelines. Peritoneal malignancy surgeons and medical oncologists reviewed recommendations to establish a national perspective on case triage and mitigating treatment strategies. Results and Conclusions: Triage of peritoneal malignancies during this time of restricted health care resource is nuanced and requires multidisciplinary discussion with consideration of individual patient factors. Prioritization should be given to patients where delay may compromise resectability of disease, and where alternative treatment options are lacking. Mitigating strategies such as systemic chemotherapy and/or surgical deferral may be utilized with close surveillance for disease stability or progression, which may affect surgical urgency. Unique hospital capacity, and ability to manage the complex post-operative course for these patients must also be considered to ensure patient and system needs are aligned.  相似文献   
67.
Commercial α-cellulose was compression-molded to produce 1A dog-bone specimens under various operating conditions without any additive. The resulting agromaterials exhibited a smooth, plastic-like surface, and constituted a suitable target as replacement for plastic materials. Tensile and three-points bending tests were conducted according to ISO standards related to the evaluation of plastic materials. The specimens had strengths comparable to classical petroleum-based thermoplastics. They also exhibited high moduli, which is characteristic of brittle materials. A higher temperature and higher pressure rate produced specimens with higher mechanical properties while low moisture content produced weaker specimens. Generally, the strong specimen had higher specific gravity and lower moisture content. However, some parameters did not follow the general trend e.g., thinner specimen showed much higher Young’s Modulus, although their specific gravity and moisture content remained similar to control, revealing a marked skin-effect which was confirmed by SEM observations.  相似文献   
68.
69.
We tested a novel 3-D matrix transducer with respect to inter-scan reproducibility of carotid maximum plaque thickness (MPT) and volume measurements. To improve reproducibility while focusing on the largest plaque/most diseased part of the carotid artery, we introduced a new partial plaque volume (PPV) measure centered on MPT. Total plaque volume (TPV), PPV from a 10-mm segment and MPT were measured using dedicated semi-automated software on 38 plaques from 26 patients. Inter-scan reproducibility was assessed using the t-test, Bland–Altman plots and Pearson's correlation coefficient. There was a mean difference of 0.01?mm in MPT (limits of agreement: ?0.45 to 0.42?mm, Pearson's correlation coefficient: 0.96). Both volume measurements exhibited high reproducibility, with PPV being superior (limits of agreement: ?35.3?mm3 to 33.5?mm3, Pearson's correlation coefficient: 0.96) to TPV (limits of agreement: ?88.2 to 61.5?mm3, Pearson's correlation coefficient: 0.91). The good reproducibility revealed by the present results encourages future studies on establishing plaque quantification as part of cardiovascular risk assessment and for follow-up of disease progression over time.  相似文献   
70.
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