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   4333篇
  免费   279篇
  国内免费   6篇
耳鼻咽喉   41篇
儿科学   221篇
妇产科学   93篇
基础医学   568篇
口腔科学   306篇
临床医学   301篇
内科学   635篇
皮肤病学   89篇
神经病学   200篇
特种医学   96篇
外科学   764篇
综合类   71篇
一般理论   4篇
预防医学   196篇
眼科学   132篇
药学   503篇
  1篇
中国医学   44篇
肿瘤学   353篇
  2023年   40篇
  2022年   108篇
  2021年   172篇
  2020年   110篇
  2019年   128篇
  2018年   178篇
  2017年   131篇
  2016年   168篇
  2015年   149篇
  2014年   210篇
  2013年   268篇
  2012年   413篇
  2011年   401篇
  2010年   206篇
  2009年   177篇
  2008年   228篇
  2007年   219篇
  2006年   163篇
  2005年   127篇
  2004年   121篇
  2003年   89篇
  2002年   85篇
  2001年   61篇
  2000年   45篇
  1999年   44篇
  1998年   19篇
  1997年   11篇
  1996年   16篇
  1995年   14篇
  1992年   44篇
  1991年   37篇
  1990年   34篇
  1989年   41篇
  1988年   23篇
  1987年   36篇
  1986年   24篇
  1985年   20篇
  1984年   22篇
  1983年   23篇
  1981年   15篇
  1980年   10篇
  1979年   15篇
  1977年   15篇
  1976年   14篇
  1975年   14篇
  1974年   24篇
  1973年   13篇
  1972年   11篇
  1970年   9篇
  1967年   9篇
排序方式: 共有4618条查询结果,搜索用时 15 毫秒
31.

The influence of fluctuating water temperature and dietary oxytetracycline (OTC) at 0 (0X), 80 (1X), 240 (3X), 400 (5X) and 800 mg (10X)/kg biomass/day for 30 consecutive days on the safety of monosex (all male) Nile tilapia Oreochromis niloticus fries in terms of feeding, growth, survival and histopathology of vital organs were assessed. A dose-dependent decline in feed intake and biomass was recorded. The OTC-dosed groups recorded higher mortalities than the control. The therapeutic OTC-dosing (1X) in conjunction with low temperature caused 75.56 ± 8.01% mortality and 25.75% reduced feed intake in 30 days. The mortalities increased with increasing OTC-doses from 85.19 ± 3.39% (1X) to 95.56 ± 2.22% (10X) and fluctuating temperature (12.00–21.50°C) even after the withdrawal of OTC. Relatively mild to moderate histopathological lesions were observed in the kidney, liver and intestine of OTC-dosed fries. These results suggested that dietary OTC and low water temperature may cause adverse effects on monosex O. niloticus fries.

  相似文献   
32.
We describe the clinical and demographic characteristics, virological follow-up, and management of five confirmed monkeypox cases from New Delhi, India without any international travel history. The viral load kinetics and viral clearance were estimated in oropharyngeal swabs (OPS), nasopharyngeal swabs (NPS), EDTA blood, serum, urine, and various lesion specimens on every fourth day of follow-up ranging from 5 to 24 post onset day (POD) of illness. All five cases presented with mild to moderate-grade intermittent fever, myalgia, and lesions on the genitals, groins, lower limb, trunk, and upper limb. Four cases had non-tender firm lymphadenopathy. No secondary complications or sexually transmitted infections were recorded in these cases except for the presence of viral hepatitis B infection marker hepatitis B virus surface antigen (HBsAg) in one case. All the cases were mild and had a good recovery. A higher viral load was detected in lesion fluid (POD 9), followed by lesion roof (POD 9), urine (POD 5), lesion base (POD 5), and OPS/NPS (POD 5). The monkeypox virus (MPXV) DNA was detected in clinical samples from 5th to 24th POD. These monkeypox cases without international travel history suggest the underdiagnosed monkeypox infection in the community. This emphasizes the need for active surveillance of MPXV in the high-risk population such as men having sex with men and female sex workers.  相似文献   
33.
In 1992 at Vivekanand Hospital in Latur, Maharashtra State, India, researchers randomly allocated 326 pregnant women, 15-45 years old, at full term, to either the modified squatting position group (study group) or the normal lithotomy delivery position group (control group) to determine whether the modified squatting position using a birth cushion has any advantages over the normal delivery position. The U-shaped cushion is inexpensive, constructed with coir and foam, and has a washable cover. Its two handles provide the woman support as she pushes and delivers the newborn. There were 145 women in the study group and 181 in the control group. Women in the squatting position did not receive any episiotomies. They spent less time pushing (i.e., in second stage of labor) than those in the control group (median, 21.2 vs. 39.32 min; p 0.01), especially among gravidae 2 and above. The time required to perform vaginal operative delivery was much shorter for the squatting position than for the normal delivery position (11.6 vs. 28.86 min; p 0.01). Fetal stress was more common among newborns delivered by the normal delivery position than among those delivered by the squatting position (7.73% vs. 3.44%; p 0.05). Women in the squatting group were more likely to have an intact perineum after delivery than those in the control group. None of the women in the control group had postpartum vulval edema, while five in the study group did. The edema was mild, however, and resolved itself within 24 hours of delivery. Most women in the squatting position group were satisfied with this position. These findings suggest that the squatting position using a birth cushion has more benefits than the normal delivery position. It allows better coordination and more effective pushing. Traditional birth attendants and female health workers at subcenter and primary health center levels can be trained to use the birth cushion during labor.  相似文献   
34.
BACKGROUND: This study was undertaken to evaluate the long-term smoking cessation efficacy of varying doses of transdermal nicotine delivery systems 4 to 5 years post-quit day. METHODS: A follow-up study was conducted 48 to 62 months after quit day among patients who were enrolled in the Transdermal Nicotine Study Group investigation. The latter study included group smoking cessation counseling and randomized assignment to 21, 14, or 7 mg nicotine patches or placebo patches. Seven of nine smoking cessation research centers participated in the long term follow-up investigation. RESULTS: The self-reported continuous quit rate among patients originally assigned 21 mg (20.2%) was significantly higher than rates for patients assigned 14 mg (10.4%), 7 mg (11.8%), or placebo patches (7.4%). Log rank survival analysis found no difference in relapse rates after 1 year postcessation. Smokers under age 30 years were significantly less likely to be abstinent at long term follow-up compared to smokers > or = 30 years of age (3 vs 13%, respectively). Mean weight gain in confirmed continuous quitters was 10.1 kg in men and 8.0 kg in women. Of the 63 continuous abstainers surveyed, 30 respondents (48%) reported that they no longer craved cigarettes, and no individual reported daily craving for cigarettes. CONCLUSIONS: Nicotine patch therapy with 21 mg/day patches resulted in a significantly higher long-term continuous abstinence rate compared to lower dose patches and placebo. Relapse rates among the various treatment conditions were similar after 1 year postcessation.  相似文献   
35.
In this prospective study, birth weight of 304 babies born at Kamla Nehru Hospital Pune during study period was recorded. From these 304 babies, babies with birth weight above 2000 grams were selected (260 babies) to prepare growth velocity curves. Daily weight of these 260 babies was recorded for 30 days. The mean birth weight of study population was 2742.5 grams. Among the daily weight recorded babies, all the babies lost weight ranging from 92 to 218 grams (mean 121 grams) after birth. The weight loss continued upto 5 days. Days required to gain weight equal to birth weight ranged from 5 to 13 days. Total weight gain observed in 30 days was 734.7 grams. Predictive value of these curves was tested in 49 infants. Deviation upto 50 grams of predicted birth weight from actual birth weight was observed in 90% of babies on day-2, 79% on day-4, 65% on day-8 and 39% on day-30.  相似文献   
36.
With improved knowledge of the anatomy and increased collaboration between the neurosurgeon and the otolaryngologist, successful surgical resection of skull-based tumors is being achieved with reduced mortality and morbidity. In spite of this, there remains a group of patients in whom an alternate surgical approach of stereotaxis may be indicated. This group of patients includes those in whom only biopsy is required, or those in whom brachytherapy using high-intensity (125)I is planned because the patients' general condition is not good enough to undergo open surgical resection of the tumor or the tumor is unresectable or the patient refuses open surgery. This article presents a preliminary report on stereotactic approach to skull base lesions with special emphasis on the technique.  相似文献   
37.
A study undertaken in a randomly selected village with a population of 695, a majority of whom were agriculturalists or laborers living in huts or mud houses. All couples in the reproductive age group (125) were interviewed in their homes, husbands and wives separately. Couples belonged to Hindu, Muslim, and Scheduled Caste groups. Of the 250 respondents, 120 were literate. About 96% were aware that births could be prevented, with vasectomy and tubectomy the best known methods. Nearly all the respondents gave friends and relatives as the source of their information; family planning workers and posters were given as the source by less than 1/2. 86% of thoce aware of contraceptive methods found family planning acceptable, most expressing the idea that a small family was easier to raise. All of the 14% opposed to family planning were Muslims whose opposiition stemmed from their religious beliefs. 44 of the couples had adopted family planning -- 24 husbands having had vasectomies and 20 of the wives tubectomies. The reasons most often given for not accepting family planning were desire for more chidlren and fear of complications. Of the sterilized respondents, a large number of the men complained of side effects, and 5 of the women complained of excessive bleeding. All of those who expressed complaints said they would not recommend the operation. It is concluded that while awareness of family planning is at an acceptable level, the problem is to make family planning itself acceptable. 1 recommendation is that sterilized couples should receive special medical attention to make their experiences more positive.  相似文献   
38.
39.
Genistein, tyrphostin and piceatannol, which are specific inhibitors of protein tyrosine kinase, were screened for their effects on the motility of intact and demembranated hamster spermatozoa. Of the three inhibitors only piceatannol inhibited the motility of intact spermatozoa. None of the inhibitors had any inhibitory effect on the reactivation of motility of demembranated hamster spermatozoa. Taken together these results indicated that a protein tyrosine kinase associated with the membrane of hamster spermatozoa was probably involved in sustenance of hamster sperm motility. Therefore in the present study a membrane-associated protein tyrosine kinase was purified from a detergent-soluble extract of plasma membranes of mature hamster spermatozoa. The purification involved cation exchange chromatography on fast protein liquid chromatography (FPLC) followed by affinity chromatography either on an antiphosphotyrosine antibody agarose or poly glu-tyr agarose column. The pure protein tyrosine kinase had an apparent molecular mass of 45 kDa. The enzyme was not inhibited by genistein or herbimycin but was inhibited by piceatannol. This is the first report on the purification of a sperm plasma membrane-associated protein tyrosine kinase, an enzyme which has also been implicated in hamster sperm motility.  相似文献   
40.
Naproxen‐2‐nitrooxyethylester (S‐(+)‐2‐(6‐methoxy‐2‐naphthyl)propanoic acid‐2‐nitrooxyethylester, LE‐EK06) was synthesized from naproxen and 2‐nitrooxyethylbromide as a novel nitric oxide–releasing derivative of naproxen. Molar equivalents of LE‐EK06 (6.93–27.73 mg/kg, p.o.) to naproxen dose‐dependently exhibited greater antinociceptive activity in comparison to naproxen in a writhing assay. The compound (5.54–22.18 mg/kg, p.o.) showed greater anti‐inflammatory activity at 2 h after as comparable to its effect at 4 h after carrageenan challenge in rats. Further, LE‐EK06 (9.45 mg/kg, p.o.) was more potent in the carrageenan‐evoked hyperalgesia. LE‐EK06 (11.09 mg/kg, p.o.) and naproxen (8.0 mg/kg, p.o.) showed a comparable inhibitory effect on exudate formation and migration of polymorphonuclear leukocytes (PMNs) in a carrageenan‐induced pleurisy test. Further, the compound (11.09 mg/kg, p.o.) significantly reduced myeloperoxidase activity in carrageenan‐treated paw and demonstrated significantly less gastrotoxicity in acute and chronic (21 days) studies. The scanning electron microscopy revealed that LE‐EK06 showed only mild gastric damage (slight disruption of mucus layer) in comparison to naproxen. The present study suggested that naproxen‐2‐nitrooxyethylester (LE‐EK06) represents a novel gastric sparing NSAID. Drug Dev. Res. 61:66–78, 2004. © 2004 Wiley‐Liss, Inc.  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