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   4812篇
  免费   198篇
  国内免费   15篇
耳鼻咽喉   34篇
儿科学   85篇
妇产科学   72篇
基础医学   704篇
口腔科学   140篇
临床医学   313篇
内科学   1234篇
皮肤病学   45篇
神经病学   342篇
特种医学   178篇
外科学   638篇
综合类   33篇
预防医学   187篇
眼科学   89篇
药学   476篇
中国医学   4篇
肿瘤学   451篇
  2023年   29篇
  2022年   52篇
  2021年   70篇
  2020年   48篇
  2019年   50篇
  2018年   72篇
  2017年   59篇
  2016年   80篇
  2015年   71篇
  2014年   102篇
  2013年   124篇
  2012年   214篇
  2011年   236篇
  2010年   150篇
  2009年   131篇
  2008年   246篇
  2007年   295篇
  2006年   255篇
  2005年   233篇
  2004年   260篇
  2003年   184篇
  2002年   221篇
  2001年   194篇
  2000年   201篇
  1999年   188篇
  1998年   54篇
  1997年   56篇
  1996年   47篇
  1995年   38篇
  1994年   37篇
  1992年   124篇
  1991年   81篇
  1990年   63篇
  1989年   90篇
  1988年   77篇
  1987年   51篇
  1986年   61篇
  1985年   58篇
  1984年   30篇
  1983年   24篇
  1980年   19篇
  1979年   23篇
  1975年   19篇
  1974年   26篇
  1973年   27篇
  1972年   23篇
  1971年   19篇
  1970年   34篇
  1969年   19篇
  1966年   18篇
排序方式: 共有5025条查询结果,搜索用时 15 毫秒
51.
52.
Newly designed intravaginal polyurethane sponges containing the spermicide nonoxynol-9 were developed for contraceptive purposes. The sponges were made by the polymerization of urethane monomers in a solution of nonoxynol-9. This new biomaterial is analogous to a large, thick cervical cup with a dimple in the center for ease of insertion and positioning to the cervix (and external os). There is no need for precoital planning or preparation for usage of this sponge. The release of the spermicidal agent from the sponges was 1st determined by soaking the sponges in saline and squeezing the nonoxynol-9 solution from them. In order to determine the actual amount of nonoxynol-9 released from the sponge, 2 analytic techniques were used. 1 method was ultraviolet spectoscopy and its accuracy ranged from 85-97%. The other was bioassay for the spermicidal activity and its accuracy ranged from 100-124%. To simulate the actual wearing of the sponge by a patient, the sponges were soaked in a large volume of saline and almost 50% of the spermicidal agent was released during the first 24 hours. In conjunction with the laboratory studies, a limited study to determine acceptability of the devices was investigated in normal women. The women were asked to wear the sponges for 1, 2, 3, 4, 5, 6, and 7 consecutive days. It was found that all women in the population could not tolerate the sponge longer than 5 days due to the odor. Thus, with the good release rates for 2-4 days and patient acceptability for 2 days of wear, a protocol for the use of the intravaginal sponge as a 2-day device was established. (author's)  相似文献   
53.
A 60-year-old obese woman was admitted to our hospital to receive surgical treatment for "slow-growing mediastinal lipoma". With the non-invasive examination such as CT scan and ultrasonography, she was revealed as Morgagni's hernia containing a greater omentum. With a trans-abdominal approach, we could take a good surgical field for the bilateral foramina of Morgagni. Several discussions were described for availability of CT scan, ultrasonography and a trans-abdominal approach.  相似文献   
54.
55.
Development of rotary blood pump technology: past, present, and future   总被引:5,自引:0,他引:5  
Even though clinical acceptance of a nonpulsatile blood flow was demonstrated almost 45 years ago, the development of a nonpulsatile blood pump was completely ignored until 20 years ago. In 1979, the first author's group demonstrated that completely pulseless animals did not exhibit any abnormal physiology if 20% higher blood flows were provided to them. However, during the next 10 years (1979-1988), minimum efforts were provided for the development of a nonpulsatile, permanently implantable cardiac prosthesis. In 1989, the first author and his team at Baylor College of Medicine initiated a developmental strategy of various types of nonpulsatile rotary blood pumps, including a 2-day rotary blood pump for cardiopulmonary bypass application, a 2 week pump for ECMO and short-term circulatory assistance, a 2 year pump as a bridge to transplantation, and a permanently implantable cardiac prosthesis. Following the design and developmental strategy established in 1989, successful development of a 2-day pump (the Nikkiso-Fairway cardiopulmonary bypass pump) in 4 years (1989-1993), a 2 week pump (Kyocera gyro G1E3 pump) in 6 years (1992-1998), and a bridge to transplant pump (DeBakey LVAD-an axial flow blood pump) in 10 years (1988-1998) was made. Currently, a permanently implantable centrifugal blood pump development program is successfully completing its initial Phase 1 program of 5 years (1995-2000). Implantation exceeded 9 months without any negative findings. An additional 5 year Phase II program (2000-2005) is expected to complete such a device that will be clinically available.  相似文献   
56.
We report a case of a long-term survivor with malignant melanoma of the anus who did not undergo radical surgery. A 71-year-old woman who presented with anal bleeding and anal tumor underwent an excisional biopsy in September 1985. The biopsy specimen was a lobulated, polypoid, pigmented mass 2 cm in diameter, that had been located on the anterior wall of the anus. A satellite nodule 7 mm in diameter was found on the left wall of the anus at the level of the dentate line. Both tumors were histologically diagnosed as malignant melanoma. The primary tumor was 6 mm thick. Melanoma cells were present microscopically at the cut end of the rectum. Because of her history of ischemic heart disease, the patient rejected our recommendation that she undergo radical surgery, and received 10 courses of carboplatin 20 mg intramuscularly and OK-432 10 K.E. (Klinische Einheit) intradermally every week. A single, pigmented metastatic inguinal lymph node developed and was excised in June 1987. A recurrent tumor was detected in the rectum in October 1992, so again we recommended radical surgery. The patient rejected radical surgery again, and received 12 courses of carboplatin 10 mg intramuscularly every 2 weeks. She died of disease at home in July 1993 after surviving for 7 years and 10 months. An autopsy was not performed. This case shows that local excision of the primary lesion may be appropriate to preserve the quality of life of patients with early-stage malignant melanoma of the anus.  相似文献   
57.
We constructed a question and answer system for direct delivery of E-mail queries from the general public to the proper hospital representative and with which the system administrator can monitor E-mail replies. The system consists of two sub-systems; one is an E-mail questionnaire sub-system that automatically delivers E-mail queries to the proper person and an E-mail reply monitor sub-system with which the system administrator can monitor the E-mail replies. The monitor system compares the origin address of the E-mail reply and the destination address on a questionnaire filled out at the time the query is made. In a test of the system, 56 queries were received in 31 days, with 37 replied to. The interval from receipt of an E-mail query to reply was calculated. Nineteen replies were submitted within 2 days.  相似文献   
58.
Subcutaneous injection of formalin into a paw of mice caused two distinct phases of licking and biting, first phase (1-5 min) and the second phase (7-30 min) after the injection. The muscarinic antagonist atropine (0.1-10 ng, i.t.) and the M(3) receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) (0.1-20 ng, i.t.) inhibited the second phase of this response, whereas higher doses of atropine (20-100 ng, i.t.) did not cause inhibition. The M(1) muscarinic receptor antagonist pirenzepine (10-100 ng, i.t.) did not inhibit either the first or the second phase response, but a high dose of pirenzepine (1000 ng, i.t.) tended to inhibit the second phase response. On the other hand, the M(2) muscarinic receptor antagonist 11-?(2-[(diethylamino)methyl]-1-piperidinyl?acetyl)-5, 11-dihydro-6H-pyrido(2,3-b)(1,4)benzodiazepine-6-one (AF-DX116; 10-1000 ng, i.t.) had no effect on either the first or the second phase of response. The opioid receptor antagonist naloxone did not affect the 4-DAMP-induced anti-nociceptive response. The i.t. injection of the acetylcholinesterase inhibitor neostigmine (25 ng) significantly inhibited only the second phase. The acetylcholine (ACh) depletor hemicholinium-3 (HC-3) (1 microg, i.t.) completely abolished the 4-DAMP-induced anti-nociceptive response. The ACh content of the spinal cord was significantly increased 14 min after formalin injection. This significant increase in the ACh content was inhibited by pretreatment with 4-DAMP (10 ng, i.t.). These results suggest that endogenous ACh in the spinal cord acts as a transmitter anti-nociception, and that ACh release regulated by presynaptic M(3) muscarinic receptors in the spinal cord is involved in the second phase of nociception induced by formalin.  相似文献   
59.
pGlu-Asn-Cys (Cys)-Pro-Arg-Gly-NH(2) (AVP(4-9)), a major metabolite C-terminal fragment of Arginine(8)-vasopressin (AVP), improves the disruption of the learning and memory, and is a far more potent in the mnemonic function than AVP. In this study, we pharmacologically characterized its putative binding site and mechanism of intracellular signaling. Radioligand binding assay showed that [35S]AVP(4-9) could detect specific binding sites in the rat hippocampus membrane preparations, and the binding site was specifically displaced by AVP(4-9) but not by either V(1) or V(2) antagonists. Furthermore, [35S]AVP(4-9) could not detect the cloned rat V(1a), V(1b) and V(2) vasopressin receptors. Even at a low doses (10-100 pM), AVP(4-9) caused an increase in both inositol(1,4, 5)-trisphosphate (Ins(1,4,5)P(3)) and intracellular calcium concentrations ([Ca(2+)](i)) in rat hippocampal cells. The AVP(4-9)-induced [Ca(2+)](i) increase was partially inhibited by the absence of Ca(2+) or by Ca(2+)-channel blocker, suggesting that AVP(4-9) caused the [Ca(2+)](i) increase via release from intracellular calcium store as well as influx from extracellular calcium. For the first time, this study provides evidence to show that AVP(4-9) activates Ins(1,4,5)P(3)/[Ca(2+)](i) pathway through a novel type of receptor in rat hippocampus, which might be potentially important in improving the mnemonic function.  相似文献   
60.
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