全文获取类型
收费全文 | 100739篇 |
免费 | 6150篇 |
国内免费 | 437篇 |
专业分类
耳鼻咽喉 | 1114篇 |
儿科学 | 2514篇 |
妇产科学 | 1783篇 |
基础医学 | 12481篇 |
口腔科学 | 1755篇 |
临床医学 | 10662篇 |
内科学 | 20281篇 |
皮肤病学 | 1341篇 |
神经病学 | 10100篇 |
特种医学 | 3902篇 |
外国民族医学 | 3篇 |
外科学 | 16341篇 |
综合类 | 1083篇 |
一般理论 | 131篇 |
预防医学 | 8253篇 |
眼科学 | 2080篇 |
药学 | 6511篇 |
中国医学 | 105篇 |
肿瘤学 | 6886篇 |
出版年
2023年 | 566篇 |
2022年 | 937篇 |
2021年 | 2099篇 |
2020年 | 1327篇 |
2019年 | 2104篇 |
2018年 | 2556篇 |
2017年 | 1827篇 |
2016年 | 1992篇 |
2015年 | 2276篇 |
2014年 | 3450篇 |
2013年 | 4735篇 |
2012年 | 7571篇 |
2011年 | 7987篇 |
2010年 | 4587篇 |
2009年 | 4137篇 |
2008年 | 7129篇 |
2007年 | 7452篇 |
2006年 | 7184篇 |
2005年 | 6894篇 |
2004年 | 6720篇 |
2003年 | 6050篇 |
2002年 | 5712篇 |
2001年 | 838篇 |
2000年 | 559篇 |
1999年 | 891篇 |
1998年 | 1220篇 |
1997年 | 924篇 |
1996年 | 748篇 |
1995年 | 684篇 |
1994年 | 591篇 |
1993年 | 579篇 |
1992年 | 441篇 |
1991年 | 400篇 |
1990年 | 323篇 |
1989年 | 292篇 |
1988年 | 279篇 |
1987年 | 277篇 |
1986年 | 243篇 |
1985年 | 277篇 |
1984年 | 305篇 |
1983年 | 252篇 |
1982年 | 333篇 |
1981年 | 281篇 |
1980年 | 221篇 |
1979年 | 95篇 |
1978年 | 128篇 |
1977年 | 108篇 |
1976年 | 78篇 |
1975年 | 66篇 |
1973年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
Edward T Mannix Melanie Roberts Daniel P Fagin Brandie Reid Mark O Farber 《The Journal of asthma》2003,40(4):349-355
Athletes have a high prevalence (11-50%) of exercise-induced asthma, which may be caused by the hyperventilation accompanying repetitive bouts of strenuous exercise. We hypothesized that recreational exercisers would display a similar trend. Eucapnic voluntary hyperventilation (EVH) bronchoprovocation (breathing 21% O2, 5% CO2, and 74% N2 at 60% of MVV for 5 minutes) was performed to determine the prevalence of airways hyperresponsiveness (AHR) in adults (n=212, 146 males, mean +/- standard deviation, age 32 +/- 10 years) who exercised regularly (10 +/- 10 years, 31 +/- 28% of their lives): none had a previous diagnosis of asthma. AHR was defined by at least a 10%, 20%, or 25% decline in FEV1, FEF(25-75), or PEFR, respectively, by spirometry at 1, 5, 10, and 15 minutes post-EVH. Forty-one of 212 (19%) tested positive for AHR: 20 of 41 (49%) were positive by FEV1, 28 of 41 (68%) by FEF(25-75), and 27 of 41 (66%) by PEFR. Comparing responders with nonresponders: pre-EVH lung function was equivalent, except for FEV1, which was reduced (p<0.05) in responders (96 +/- 13 vs. 102 +/- 12% predicted). Mean maximal negative deflections for responders were: for FEV1, -17 +/- 7%; FEF(25-75), -31 +/- 10%; PEFR, -38 +/- 11%. Ranges of decline for responders were: FEV1, -10 to -33%; FEF(25-75), -20 to -59%; PEFR, -25- to -70%. We conclude that in these regular exercisers, the prevalence of AHR is high and comparable with some athletic populations. 相似文献
162.
163.
A brief mechanical or electrical stimulus to peripheral nerve afferents from the upper and lower limbs elicited a small and inconsistent EMG response of the orbicularis oculi muscles. This response was facilitated when the stimuli were delivered at fixed leading time intervals, of 45–300 ms, with respect to a supraorbital nerve electrical stimulus. Also, the peripheral nerve stimulus modified the conventional blink reflex responses, inducing facilitation of R1 and inhibition of R2. These results suggest a complex processing of sensory inputs from the face and the limbs at the brainstem, where they are probably integrated in a network of interneurons influencing the excitability of facial motoneurons. 相似文献
164.
Abstract: Scabies in neonates and infants has a clinical pattern that may be easily misdiagnosed. The eruption is generalized, including involvement of the head, neck, face, palms, and soles, with an early tendency to pustule formation. Other lesions include papules, vesicles, and burrows, which may be obliterated by secondary lesions. A confusing clinical picture resulted in a delay in diagnosing scabies in a 23-day-old infant who was successfully treated with permethrin 5% cream. 相似文献
165.
Susan R. Gartner Catherine L. Gilliss Julie A. Shinn Patricia A. Sparacino Sally Rankin Maribelle Leavitt Martha Price Mark Hudes 《Journal of advanced nursing》1988,13(5):649-661
To enhance individual and family health during recovery from heart surgery, this study employed nursing interventions based on self-efficacy and family stress theory during the hospitalization period and for 3 months thereafter. The effectiveness of the interventions were assessed through a randomized trial in which 67 prospective bypass and valve surgery patients, aged 30-77 years, and their spouses, were allocated either the experimental interventions or usual care and followed for 6 months. At 3 months post-surgery, the only statistically significant differences between the experimentals and controls were on perceived self-efficacy for lifting and tolerating emotional distress. At 6 months no significant differences were found on individual or family measures. Analyses revealed that age, gender and preoperative cardiac status significantly affected individual recovery. The study is continuing with a larger sample in order to explicate the recovery process and to better determine whether a low intensity nursing intervention can effect changes in individual and family recovery. 相似文献
166.
Mark Warner George Eapen George W. Vetrovec 《Catheterization and cardiovascular interventions》1992,25(2):148-150
We describe a patient with two separate vessels having different origins supplying the circumflex coronary artery distribution. This represents a previously undescribed coronary artery anomaly. 相似文献
167.
In this study, large areas of goldfish telencephalon were ablated including rostral nucleus preopticus periventriculare (rNPP), and degenerating axons were traced by a modified Fink and Heimer procedure. The lesioning procedure ablated large regions of area dorsalis telencephali pars medialis, centralis, and dorsolateral complex; and completely removed area ventralis telencephali pars dorsalis, ventralis, and lateralis. In addition, the supracommissural nucleus and rNPP were lesioned specifically because both nuclei have been thought to be involved in courtship behavior and endocrine control of reproduction. This investigation demonstrated extensive fiber projections from telencephalic nuclei and/or rNPP to the hypothalamus. Lesioned telencephalon and/or rNPP projected bilaterally to nucleus preopticus and the suprachiasmatic nucleus and unilaterally to the following tuberal nuclei: nucleus anterior tuberis, and the lateral hypothalamic nucleus. A much larger fiber projection to the inferior lobe nuclei was also observed with a large contralateral as well as ipsilateral input. 相似文献
168.
Mark A. Trifiro Parsa Kazemi-Esfarjani Leonard Pinsky 《Trends in Endocrinology and Metabolism》1994,5(10):416-421
X-linked muscular atrophy is a form of adult-onset, usually slowly progressive spinal and bulbar motor neuron degenerative disease that is uniquely associated with male hypogonadism. The mutation responsible for this syndrome is expansion of the trinucleotide repeat—cytosine (C), adenine (A), guanine (G)—in a 5′-translated portion of the androgen receptor (AR) gene from a normal, polymorphic length of n = 11–31 to n ≥ 40. The resulting androgen receptor (AR) protein has an expanded polyglutamine tract in its NH2-terminal modulatory domain, and is postulated to lose a basic, intrinsic function that causes a mild form of androgen insensitivity; however, almost certainly, it also gains a novel, extrinsic function that is selectively neuronotoxic. The unexplained mechanism that culminates in this form of neuronspecific death is the prototype for three different adult-onset neuronopathies that are caused by (CAG)n expansions in other genes. 相似文献
169.
Dr. Stanford S. Jhee Pharm.D. Dr. Jack W. Kern Pharm.D. Dr. Jin-Pil Burm Ph.D. Dr. Albert E. Yellin M.D. Dr. Mark A. Gill Pharm.D. FASHP FCCP 《Pharmacotherapy》1995,15(4):472-478
Study Objective . To determine the appropriate compartmental and noncompartmental pharmacokinetic parameters for intravenous piperacillin and tazobactam. Design . Sequential selection of patients entered into a randomized, open-label clinical efficacy trial. Setting . Los Angeles County-University of Southern California Medical Center. Participants . Sequential sample of 18 patients admitted for intraabdominal infections and consented into a comparative antibiotic trial. Interventions . Patients received piperacillin 4 g plus tazobactam 500 mg by intravenous intermittent infusion every 8 hours. Measurements and Main Results . The estimated noncompartmental pharmacokinetic parameters (mean ± SD) for piperacillin and tazobactam, respectively, were as follows: maximum concentration in plasma 218.7 ± 48.9 μg/ml and 27.8 ± 9.1 μg/ml; half-life 1.07 ± 0.22 hours and 1.00 ± 0.27 hours; elimination rate constant 0.67 ± 0.13 hr−1 and 0.73 ± 0.18 hr−1; area under the concentration-time curve from zero hour to infinity 288.5 ± 71.25 mg·hr/L and 36.3 ± 9.55 mg·hr/L; total plasma clearance 14.75 ± 3.93 L/hour and 14.78 ± 4.39 L/hour; renal clearance 5.69 ± 1.94 L/hour and 7.85 ± 3.37 L/hour; volume of distribution at steady state 21.00 ± 4.18 L and 22.47 ± 8.27 L; and mean residence time 1.72 ± 0.29 hours and 1.79 ± 0.35 hours. Conclusion . Our findings were similar to those in other surgical patient models. The two-compartmental model best described piperacillin and tazobactam disposition in our patients. Bayesian analyses of the two-compartment models of piperacillin and tazobactam were able to predict trough, peak, and 2-hour postadministration levels without bias. 相似文献
170.
Effects of alkyl chain length on the inhibition of NNK-induced lung neoplasia in A/J mice by arylalkyl isothiocyanates 总被引:4,自引:1,他引:3
Morse Mark A.; Eklind Karin I.; Amin Shantu G.; Hecht Stephen S.; Chung Fung-Lung 《Carcinogenesis》1989,10(9):1757-1759
Six homologous arylalkyl isothiocyanates were evaluated fortheir abilities to inhibit pulmonary adenomas induced by thetobacco-specific nitrosamine 4-(methylnitrosamino)-l-(3-pyridyl)-1-butanone(NNK) in A/J mice. Four consecutive daily doses (5 µmol/mouse)of phenyl isothiocyanate (PITC), benzyl isothiocyanate (BITC),phenethyl isothiocyanate (PETTC), 3-phenylpropyl isothiocyanate(PPITC), 4-phenylbutyl isothiocyanate (PBITC), 4-oxo-4-(3-pyridyl)-butylisothiocyanate (OPBITC) and corn ofl were administered to miceby gavage. Two hours following the final dosing, mice were administeredsaline or 10 µmol of NNK in saline i.p. Pulmonary adenomaswere counted at 16 weeks after NNK administration. The miceadministered only corn oil prior to NNK developed an averagemultiplicity of 9.2 tumors/ mouse. Pretreatment with PITC, BITCand OPBITC had no significant effects on NNK-induced lung neoplasia.However, PEITC pretreatment resulted in a 64% reduction of lungtumor multiplicity, but did not affect the percentage of micethat developed tumors. Both PPITC and PBITC decreased tumormultiplicity by 96% and the percentage of tumor-bearing animalsby >60%. These results, in conjunction with our previouswork, demonstrate a general trend of increasing inhibition ofNNK-induced lung neoplasia by arylalkyl isothiocyanates withincreasing alkyl chain length. This study also demonstratesthe remarkable inhibitory activities of PPITC and PBITC, twoisothiocyanates that had not previously been tested as chemopreventiveagents. 相似文献