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   3562篇
  免费   183篇
  国内免费   9篇
耳鼻咽喉   27篇
儿科学   68篇
妇产科学   55篇
基础医学   384篇
口腔科学   131篇
临床医学   251篇
内科学   914篇
皮肤病学   127篇
神经病学   235篇
特种医学   108篇
外科学   658篇
综合类   12篇
预防医学   91篇
眼科学   32篇
药学   208篇
中国医学   6篇
肿瘤学   447篇
  2023年   17篇
  2022年   40篇
  2021年   84篇
  2020年   29篇
  2019年   40篇
  2018年   62篇
  2017年   42篇
  2016年   78篇
  2015年   63篇
  2014年   90篇
  2013年   114篇
  2012年   161篇
  2011年   206篇
  2010年   126篇
  2009年   95篇
  2008年   186篇
  2007年   173篇
  2006年   148篇
  2005年   152篇
  2004年   153篇
  2003年   168篇
  2002年   175篇
  2001年   111篇
  2000年   90篇
  1999年   115篇
  1998年   47篇
  1997年   42篇
  1996年   41篇
  1995年   34篇
  1994年   29篇
  1993年   29篇
  1992年   87篇
  1991年   76篇
  1990年   57篇
  1989年   59篇
  1988年   58篇
  1987年   59篇
  1986年   50篇
  1985年   62篇
  1984年   29篇
  1983年   34篇
  1981年   15篇
  1979年   20篇
  1978年   19篇
  1977年   19篇
  1975年   17篇
  1973年   17篇
  1972年   14篇
  1969年   26篇
  1968年   16篇
排序方式: 共有3754条查询结果,搜索用时 0 毫秒
31.
32.
This study investigated the effects of 12 weeks of aerobic exercise plus voluntary food restriction on the body composition, resting metabolic rate (RMR) and aerobic fitness of mildly obese middle-aged women. The subjects were randomly assigned to exercise/diet (n = 17) or control (n = 15) groups. The exercise/diet group participated in an aerobic training programme, 45–60 min · day –1 at 50%–60% of maximal oxygen uptake (VO2max), 3–4 days · week–1, and also adopted a self-regulated energy deficit relative to predicted energy requirements (–1.05 MJ · day –1 to –1.14 MJ · day –1 ). After the regimen had been followed for 12 weeks, the body mass of the subjects had decreased by an average of 4.5 kg, due mainly to fat loss, with little change of fat free mass (m ff). The absolute RMR did not change, but the experimental group showed significant increases in the RMR per unit of body mass (10%) and the RMR per unit of m ff (4%). The increase in RMR/m ff was not correlated with any increase in VO2max/m ff. The resting heat production per unit of essential body mass increased by an average of 21%, but the resting heat production rate per unit of fat tissue mass remained unchanged. We concluded that aerobic exercise enhances the effect of moderate dietary restriction by augmenting the metabolic activity of lean tissue.  相似文献   
33.
The isothermal and chimeric primer-initiated amplification of nucleic acids (ICAN) is a new isothermal DNA amplification method composed of exo Bca DNA polymerase, RNaseH and DNA-RNA chimeric primers. We developed the simultaneous detection system for Chlamydia trachomatis/Neisseria gonorrhoeae DNA, combined with luminescence detection by a probe hybridization. In the performance tests, this system was able to detect 10 to 100 copies of C. trachomatis/N. gonorrhoeae DNA for only 3.5 hours, and was highly specific to C. trachomatis/N. gonorrhoeae without any cross-reaction to C. pneumoniae, N. lactamica, N. sicca or N. meningitidis. When we tested 60 clinical samples of urine and cervical swabs, the interpretive results were completely consistent with those obtained by Roche PCR system. Of 13 positive samples by the ICAN and PCR systems for C. trachomatis, four were negative by EIA method(IDEIA Chlamydia). These results indicate that the ICAN system is an efficient and sensitive system to simultaneously detect C. trachomatis/N. gonorrhoeae DNA.  相似文献   
34.
Influenza virus overcomes apoptosis by rapid multiplication   总被引:1,自引:0,他引:1  
The kinetics of apoptotic fragmentation of the chromosomal DNA was determined in the influenza virus-infected MDCK, HeLa and KB cells, respectively. Comparison of these kinetics with the kinetics of virus multiplication revealed that the multiplication of influenza virus was observed only when apoptosis was induced after the production of progeny virus in the infected cells. The extent of apoptotic response was reversely correlated with the permissiveness of the cells.  相似文献   
35.
Three polyurethane materials were prepared by removing and adding the leachable oligomers from and to the same polyetherurethane (PEU). The three PEU materials were dissolved in tetrahydrofuran (THF) and dimethyformamide (DMF) and the solutions were cast on a glass plate to make films of smooth and foamed surfaces, respectively. These six materials and polydimethylsioxane (silicone) were implanted into subcutaneous pocket of rats for 2 years to evaluate the long-term effects around the implant. Among the smooth surface implants, PEU materials induced a higher incidence of tissue responses, including tumor formation than silicone. However, no relationship between the oligomer content and the tissue responses was found. Changing surface morphology from a smooth to a foamed one prolonged the latent period of tumor development and decreased the total tumor incidence.  相似文献   
36.
37.
A 48-year-old man consulted us with the chief complaints of right flank mass. On examination, there was a soft bulge on the right superior lumbar area. Since computed tomographic scanning showed subcutaneous fatty tissue, we suspected a superior lumbar hernia. The diagnosis was confirmed by magnetic resonance imaging (MRI) that revealed a lumbar muscle defect and prolapsed fatty tissue around the kidney. During the operation, a small hernia hiatus, 2 cm in width, opened in the superior lumbar triangle. The herniated fatty tissue was excised, and the defect of fascia was closed by overlapping the adjacent fascial structure. No signs of recurrence were found at 3 months postoperatively. The usefulness of MRI for the diagnosis is discussed and previous literature is reviewed.  相似文献   
38.
PURPOSE: Psychogenic lower urinary tract dysfunction (PLUTD) is composed of two syndromes; psychogenic frequency-urgency syndrome (PFUS) and psychogenic urinary retention (PUR). We evaluated the patho-physiology of PFUS and PUR, and explored the different pathogenesis in these syndromes. MATERIAL AND METHODS: Forty five patients with PLUTD, consisting of 23 patients with PFUS and 22 patients with PUR were investigated by using the psychological tests: CMI (Cornell Medical Index) and TEG (Todai's Egogram), a quantitative perspiration test in 45 females (23 patients with PFUS and 22 patients with PUR), and simultaneous measurements of voiding cysto-urethrography and urodynamic studies using the Life-Tech 6 channel polygraph in 35 patients (17 patients with PFUS and 18 patients with PUR). RESULTS: The prevalence in ages revealed two peaks, 20 years and 50 to 60 years. Over 25% of them had pyuria more than 10/hpf of WBC. Peak flow rate measured by uroflowmetry showed normal range in PFUS group and decreased in PUR group. The functional vesical volume was less than 100 ml in most patients with PFUS. Residual urine in PUR group was significantly greater. Capacity of the PFUS group were able to hold over 400 ml of contrast instilled through the urethral catheter, despite increased desire to void. Over 15% of the study group with PFUS showed uninhibited systolic contraction of detrusor (> 15 cm H2O) during filling phase. The measurement value of urodynamic parameters demonstrated that a periodic follow-up survey of the upper urinary tract should be performed because of the low compliance bladder in the patients with PLUTD. During voiding phase, the women with PFUS had a tendency to be divided into two groups, hypercontractile or acontractile detrusor. The voiding cysto-urethrography (VCUG) showed a tendency of bladder neck opening on patients with PFUS during filling phase. Most of PLUTD cases demonstrated a round to triangle shape on vesical configuration, which led to a spastic condition of detrusor muscle. We attempted to measure the quantitative perspiration using 3 kinds of loading tests; respiratory, arithmetic and psychological load. In the psychological loading test, we asked 98 questions about their daily lives including occupation, living condition, family relationship and sexual activities. Arithmetic loading test consisted of counting in reverse, subtraction and multiplication. The quantitative perspiration rate resulted in a "positive" in many patients with PFUS. Respiration loading test was performed to measure the respiration volume during 3 large inhales. Most patients with PUR tested within the normal range for respiration except for those patients with decreased or no perspiration during the psychiatric loading test. These results may reflect the psychological elements including suppression and subconscious defense mechanism. Neurosis which was diagnosed as having type III to type IV of the Cornell Medical Index was demonstrated in less than under 40% of patients with PFUS and more than 55% patients with PUR. There was no significant trend or difference between PFUS and PUR detected from Todai's Egogram. CONCLUSIONS: Due to the reflection of many psychological responses, it is necessary to investigate from various examinations including psychological, autonomical and classical urological studies for accurate diagnosis of PLUTD.  相似文献   
39.
22-Oxacalcitriol ameliorates high-turnover bone and marked osteitis fibrosa in rats with slowly progressive nephritis. BACKGROUND: 22-Oxacalcitriol (OCT) is a unique vitamin D analogue with less calcemic activity than calcitriol, and it effectively suppresses parathyroid hormone (PTH) secretion in uremic rats. This study was performed to examine the long-term effect of intravenously administered OCT on high-turnover bone disease in model rats of slowly progressive renal failure. METHODS: Slowly progressive renal failure rats were made by a single injection of glycopeptide isolated from rat renal cortical tissues. At 250 days, glycopeptide-induced nephritis (GN) rats were divided into three groups with the same levels of serum creatinine and PTH, and they received either OCT (0.03 or 0.15 microg/kg body wt) or vehicle given intravenously three times per week for 15 weeks. RESULTS: Renal function of GN rats deteriorated very slowly but progressively, as assessed by the increase of serum creatinine concentration. At sacrifice, serum PTH levels, bone formation markers, bone resorption markers, and fibrosis volume were significantly elevated in vehicle-treated GN rats compared with those of sham-operated rats, suggesting the development of high-turnover bone disease with osteitis fibrosa. In contrast, in the GN-OCT 0.15 microg/kg group, these high PTH levels and high-turnover bone and fibrosis were significantly decreased. Such amelioration of bone abnormalities by OCT was not accompanied by either hypercalcemia or further deterioration of renal function. CONCLUSIONS: These data indicate that OCT may be a useful and safe agent not only for the suppression of PTH, but also for the amelioration of osteitis fibrosa and high-turnover bone without causing hypercalcemia in chronic dialysis patients.  相似文献   
40.
BACKGROUND: The transtentorial approach is well known as an approach to the pineal region. We have modified this approach for mediosuperior cerebellar tumors. METHODS: We describe six cases of tumor excision in this region using an occipital interhemispheric transtentorial approach. RESULTS: The lesions were easily accessible and the tumor was totally removed by this modified approach in all cases. Transient visual field disturbance with spontaneous recovery occurred in two patients. The lateral margin of the tumor was accessed easily up to 35 mm from the midline on the operative side and up to 17 mm from the midline on the contralateral side. CONCLUSION: This approach proved to be very useful for mediosuperior lesions of the cerebellum, without causing any neural structural damage, and allowed for a wider operative field.  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