全文获取类型
收费全文 | 23481篇 |
免费 | 2219篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 386篇 |
儿科学 | 727篇 |
妇产科学 | 617篇 |
基础医学 | 3127篇 |
口腔科学 | 705篇 |
临床医学 | 3095篇 |
内科学 | 4455篇 |
皮肤病学 | 429篇 |
神经病学 | 1799篇 |
特种医学 | 1095篇 |
外国民族医学 | 2篇 |
外科学 | 3265篇 |
综合类 | 366篇 |
一般理论 | 13篇 |
预防医学 | 2177篇 |
眼科学 | 417篇 |
药学 | 1571篇 |
3篇 | |
中国医学 | 59篇 |
肿瘤学 | 1431篇 |
出版年
2021年 | 264篇 |
2020年 | 201篇 |
2019年 | 292篇 |
2018年 | 372篇 |
2017年 | 266篇 |
2016年 | 304篇 |
2015年 | 369篇 |
2014年 | 534篇 |
2013年 | 761篇 |
2012年 | 1055篇 |
2011年 | 1156篇 |
2010年 | 659篇 |
2009年 | 552篇 |
2008年 | 950篇 |
2007年 | 998篇 |
2006年 | 1025篇 |
2005年 | 942篇 |
2004年 | 1047篇 |
2003年 | 974篇 |
2002年 | 841篇 |
2001年 | 775篇 |
2000年 | 706篇 |
1999年 | 692篇 |
1998年 | 370篇 |
1997年 | 288篇 |
1996年 | 282篇 |
1995年 | 258篇 |
1994年 | 239篇 |
1993年 | 250篇 |
1992年 | 535篇 |
1991年 | 524篇 |
1990年 | 460篇 |
1989年 | 545篇 |
1988年 | 501篇 |
1987年 | 503篇 |
1986年 | 469篇 |
1985年 | 499篇 |
1984年 | 338篇 |
1983年 | 298篇 |
1982年 | 217篇 |
1981年 | 197篇 |
1979年 | 263篇 |
1978年 | 212篇 |
1977年 | 180篇 |
1976年 | 198篇 |
1975年 | 167篇 |
1974年 | 190篇 |
1973年 | 202篇 |
1972年 | 158篇 |
1971年 | 162篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Fucoidin and heparin sulfate inhibit binding of human sperm to the human zona pellucida under hemizona assay (HZA) conditions. Here we used the HZA to further assess tight sperm binding with/without preincubation of the sperm with other sulfated and nonsulfated glycoconjugates and charged polymers. Fucoidin significantly inhibited binding compared with controls (greater than 75% inhibition), even if sperm were washed after preincubation with the saccharide. Dextran sulfate also produced significant inhibition, although to a lesser extent (54% inhibition). Chondroitin sulfates A and B, heparin, and dextran did not affect binding. Sodium sulfate and polyglutamic acid did not affect HZA results; polyphosphates produced only moderate inhibition. The potent inhibitory effect of the sulfated carbohydrates fucoidin and dextran is probably competitive (receptor-ligand type) in nature. However, the lack of significant effects of simple charged molecules (nonspecific effects) suggests that the degree of sulfation (charge) may not be crucial to its inhibitory action. 相似文献
42.
R E Clark 《Academic medicine》1992,67(12):819-820
43.
R T Katz A J Haig B B Clark R J DiPaola 《Archives of physical medicine and rehabilitation》1992,73(5):403-408
We present a life-table analysis of a cohort of 29 locked-in syndrome (LIS) patients followed for a minimum of five years, and we report on the status of the chronic LIS patient. Twenty-nine LIS patients who remained locked-in for more than one year were identified. Inpatient charts were reviewed for demographic, medical, and functional data. Telephone followup was obtained to examine medical complications after discharge, survival, neurologic recovery, care issues, and permanent disposition. A life-table analysis was performed on survival data. Cerebrovascular disease was the most common cause of LIS. Survival ranged from 2.02 to 18.15 years. Twenty of the 26 patients available for five-year followup survived; hence, five-year survival was 81%. An alternative method of communication and emotional stress for the patient's caregiver was the key issue in patient care. Most patients were cared for in their own homes. Although minimal late neurologic recovery occurs in chronic LIS, survival may, nonetheless, be prolonged with adequate supportive care. Modern computerized technology offers LIS patients the ability to interact with their environment. This information may assist physicians in making ethical and long-term care decisions with the patient rather than for the patient with LIS. 相似文献
44.
B E Barton R Mayer J V Jackson M A Clark 《Immunopharmacology and immunotoxicology》1991,13(1-2):199-218
NFS60, a murine leukemia cell line, responds to both interleukin 3 and 6 by proliferating, apparently by different signal transduction pathways. Although stimulation by both cytokines increases the uptake of 3H-arachidonic acid, the response to IL-6 was much faster. Furthermore, the effect of various arachidonic acid metabolites on the response to cytokine was different. PGE2 inhibited IL-6-induced proliferation and potentiated the response to IL-3. Additionally the G proteins which coupled the IL-3 and IL-6 receptor to the proliferative response are probably different, based on the ability of cholera toxin to inhibit the IL-3 but not the IL-6 response. These data are evidence of two pathways of signal transduction. 相似文献
45.
46.
I. Litvan R. Blesa K. Clark P. Nichelli J. R. Atack M. M. Mouradian J. Grafman T. N. Chase 《Annals of neurology》1994,36(1):55-61
Severe cholinergic loss occurs in the brains of patients with progressive supranuclear palsy. To evaluate the functional implications of this neuronal deficit, dose-response curves were obtained in patients with progressive supranuclear palsy and normal control subjects undergoing intravenous cholinergic blockade (scopolamine) and stimulation (physo-stigmine). Physostigmine had no significant neurobehavioral effects at any does in patients with progressive supranuclear palsy. Scopolamine, at low and medium doses, significantly impaired memory performance of both groups, but worsened the gait of only the patients. High-dose scopolamine, which could not be tolerated by the patients, resulted in gait deterioration among control subjects. Thus, patients with progressive supranuclear palsy have increased sensitivity to cholinergic blockade compared to control subjects. Since loss of cholinergic neurons appears to contribute to the pathogenesis of certain cognitive and motor deficits found in progressive supranuclear palsy, the use of oral anticholinergics should ordinarily be avoided in this disorder. On the other hand, physostigmine at clinically tolerated dose levels seems to be terapeutically ineffective. 相似文献
47.
The voltage-gated currents of the astrocytes associated with the retinal capillaries of the rabbit retina were studied using whole-cell patch clamp recording. The resting potential of these cells was −70 ± 4.8 mV (mean ± SEM; n = 54), and the input resistance and cell capacitance were 558 ± 3.6 MΩ and 19.5 ± 1.8 pF respectively. Depolarization to potentials positive to −50 mV evoked rapidly activating inward and outward currents. The inward current was transient, eliminated by substitution of choline for Na+ in the bathing solution, and reduced by 50% in the presence of 1 μM tetrodotoxin. The time-to-peak of the Na+ current was more than twice that for the Na+ current found in retinal neurons. The glial Na+ current was half-inactivated at −55 mV. A transient component of the outward K+ current was blocked by external 4-aminopyridine while a more sustained component was blocked by external tetraethylammonium. At potentials between −150 and −50 mV the membrane behaved Ohmically. Voltage-gated currents in retinal astrocytes recorded in situ appear qualitatively similar to those described for some glial cells in vitro. 相似文献
48.
Analgesia with preoperative naproxen after laparoscopic sterilization was
assessed in a prospective, double-blind, randomized study of 80 women; 42
women received oral naproxen 1 g, approximately 90 min before surgery, and
38 received placebo. Preoperative naproxen did not significantly influence
postoperative pain scores, but was associated with a reduction in
parenteral opioid administration (P = 0.04).
相似文献
49.
50.
STUDY OBJECTIVES: To determine the current ingestants found in the multiply injured trauma patient and to determine if this select group of ingestants affected the resuscitation, evaluation, or convalescent management of these patients. DESIGN: A one-year retrospective analysis was performed on all patients who were admitted to an urban trauma center with a discharge diagnosis of multiple trauma and who received a comprehensive toxicology screening test. MAIN RESULTS: One hundred twenty-seven of the 177 patients (72%) who fulfilled the criteria had positive toxicology screens. Ethyl alcohol was the only drug present in 26 of these patients (20%); 57 (45%) were positive for drugs other than ethyl alcohol. A combination of ethyl alcohol and at least one other drug was quantified in 44 patients (35%). The most often encountered substances were ethyl alcohol (55%), marijuana (24%), and cocaine (21%). Twelve drug screens (9%) demonstrated pharmaceuticals (eg, acetylsalicylic acid, acetaminophen, or cyclic antidepressants) that may require specific antidotal treatment. CONCLUSION: The ingestant profile found in this subgroup of trauma patients differed from those of previous studies. Although a select group of these ingestants requires specific treatment or affects the physical assessment of the patient, none of these trauma patients received more than supportive care. 相似文献