全文获取类型
收费全文 | 7630篇 |
免费 | 493篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 172篇 |
妇产科学 | 351篇 |
基础医学 | 905篇 |
口腔科学 | 115篇 |
临床医学 | 855篇 |
内科学 | 1779篇 |
皮肤病学 | 79篇 |
神经病学 | 543篇 |
特种医学 | 471篇 |
外科学 | 969篇 |
综合类 | 133篇 |
一般理论 | 3篇 |
预防医学 | 377篇 |
眼科学 | 160篇 |
药学 | 558篇 |
中国医学 | 46篇 |
肿瘤学 | 632篇 |
出版年
2023年 | 46篇 |
2022年 | 81篇 |
2021年 | 193篇 |
2020年 | 96篇 |
2019年 | 159篇 |
2018年 | 209篇 |
2017年 | 152篇 |
2016年 | 121篇 |
2015年 | 231篇 |
2014年 | 292篇 |
2013年 | 384篇 |
2012年 | 575篇 |
2011年 | 522篇 |
2010年 | 317篇 |
2009年 | 339篇 |
2008年 | 453篇 |
2007年 | 390篇 |
2006年 | 389篇 |
2005年 | 398篇 |
2004年 | 358篇 |
2003年 | 290篇 |
2002年 | 239篇 |
2001年 | 219篇 |
2000年 | 183篇 |
1999年 | 191篇 |
1998年 | 79篇 |
1997年 | 53篇 |
1996年 | 56篇 |
1995年 | 55篇 |
1994年 | 42篇 |
1993年 | 28篇 |
1992年 | 108篇 |
1991年 | 80篇 |
1990年 | 82篇 |
1989年 | 67篇 |
1988年 | 76篇 |
1987年 | 78篇 |
1986年 | 70篇 |
1985年 | 73篇 |
1984年 | 67篇 |
1983年 | 33篇 |
1982年 | 28篇 |
1981年 | 18篇 |
1979年 | 38篇 |
1978年 | 28篇 |
1977年 | 26篇 |
1976年 | 21篇 |
1975年 | 36篇 |
1974年 | 23篇 |
1973年 | 19篇 |
排序方式: 共有8212条查询结果,搜索用时 15 毫秒
21.
Depression can occur in schizophrenia but can be difficult to distinguish from negative symptoms of the illness. To evaluate whether concurrent use of the Hamilton Rating Scale for Depression (HRSD) and the Brief Psychiatric Rating Scale (BPRS) could successfully separate depression and negative symptoms, we examined ratings on 69 unmedicated schizophrenic inpatients. A classical BPRS depression subscale score correlated highly (rho = 0.80) with the HRSD total score. The classical BPRS "negative symptom" subscale score was unrelated to both the BPRS and HRSD depression summary measures. Among individual HRSD items, negative symptoms correlated only with work/activities and retardation. The findings suggest that negative and depressive symptoms may be assessed independently. 相似文献
22.
23.
Yeh CC Pei RJ Liu YH Su B Lee KY Yeh KT Hsu YH Ho CC Ho HC Lai YS 《Research communications in molecular pathology and pharmacology》1999,105(1-2):3-10
The epithelium in kidneys and urinary bladders contain CK18 as in liver cells. The modulation of cytokeratin 18 during tumor transformation in hepatoma had been previously recognized through a series of biochemical and immunological approaches. A 14 KD hepatoma related molecules was found in the previous studies. We would like to utilize the hepatoma transformation model to study the changes in CK18 in transitional cell carcinoma, using immunoblotting and western blotting techniques. The result is that transitional cell carcinoma retain their CK18 molecule. Furthermore, CK18 related molecules similar to those seen in hepatoma also present in transitional cell carcinoma. The conclusions are transitional cell carcinoma contains CK18 related proteins similar to those seen in hepatoma tissues. We suggest that this element would be responsible for the change during the malignant transformation processes. 相似文献
24.
This study assessed 11C-acetate turnover (clearance) in nasopharyngeal carcinoma (NPC). Data were acquired by dynamic PET after the intravenous injection of 4.625 MBq.kg-1 body weight of 11C-acetate for 30 min. Tomograms were reconstructed and evaluated visually. A time-activity curve of the nasopharynx and neck was generated and the clearance rate of 11C-acetate from the nasopharynx in the slow phase and from NPC was calculated using 0.693/T1/2. Ten patients with nasopharyngeal carcinoma and nine normal subjects were studied. The clearance of 11C-acetate from the normal nasopharynx was rapid and biexponential, in contrast to the rapid uptake followed by extremely slow clearance in patients with NPC. The clearance rate (mean +/- S.D.) was 0.0074 +/- 0.0042 in NPC and 0.0263 +/- 0.0152 in controls in the slow phase, being significantly different between the two groups with no overlap. All nasopharyngeal carcinomas were clearly visualized, in contrast to no obvious retention in the normal nasopharynx. Our initial results indicate that 11C-acetate clearance can be used to differentiate nasopharyngeal carcinoma from a normal nasopharynx. This finding may lead to new applications of 11C-acetate in oncology. 相似文献
25.
Y Fujita T Yamada K Inoue A Sato M Katayama A Ofuji H Fujita M Yeh 《Journal of clinical neurophysiology》1999,16(1):69-76
The scalp far-field potentials after median nerve stimulation at the wrist consist of P9, P11, P13, and P14 positive components. Earlier, Emerson et al. (1984) identified the "N10" negative potential in-between the P9 and P11 and claimed that this was not merely a passive return to the baseline after the P9 positive deflection but a distinct component reflecting a proximal brachial plexus volley. They thought N10 was a far-field potential having widespread distribution with a fixed latency. In this study we found that N10 was of higher amplitude after median nerve stimulation at the elbow than after stimulation at the wrist. Indeed the N10 latency was fixed from the lower anterior neck to the scalp, and its amplitude was maximum at the anterior lower neck. The latency of N10 was about 0.3 milliseconds longer than the Erb's potential and 0.15 milliseconds longer than the potential recorded from the lateral neck on the side of stimulation. The N10 amplitude increased in parallel with increased stimulus intensity. In order to explore the origin of the N10 stationary field potential, we designed a paired stimuli paradigm applied to the wrist (S1) and to the elbow (S2). The interstimulus interval between S and S2 was adjusted so that the timing of S2 was immediately after the traveling impulse produced by the S1 stimulus as it passed through the S2 stimulus site. This technique allowed stimulation of the anterior interosseous nerve selectively at the elbow while the median nerve originating from the wrist was undergoing refractory period. The response of (S1 + S2) - S1 showed only the N10 with absence of cervical and cortical responses, implying that N10 was activated, predominantly by the interosseous nerve, i.e., an antidromic motor volley, when the median nerve was stimulated at the elbow. 相似文献
26.
Yeh SY 《Synapse (New York, N.Y.)》1999,31(3):169-177
The present study examined the effect of N-tert-butyl-alpha-phenylnitrone (PBN) on 3,4-methylenedioxmathamphetamine (MDMA)-induced depletion of serotonin in the CNS. Rats were treated with two concurrent injections of MDMA (20 mg/kg, s.c.), PBN (50-400 mg/kg dissolved in ethanol, 50 mg/ml of 25% ethanol, i.p.), saline or 25% ethanol, alone or in combination, 6 h apart, and sacrificed 5 days later. Rectal temperature was measured prior to and hourly following the drug injection for 5 h. Monoamine levels in the tissue were measured by HPLC. Density of the 5-HT transporters was assayed by [3H]paroxetine binding. Rectal temperature of rats increased after MDMA, decreased after PBN, ethanol, PBN plus ethanol, and MDMA plus ethanol, and was not significantly altered after MDMA plus PBN. Levels of 5-HT and 5-HIAA in the frontal cortex, hippocampus, striatum, and brain stem of rats decreased significantly after MDMA or MDMA plus ethanol, but not after MDMA plus PBN, PBN plus ethanol (PBN dissolved in ethanol), or ethanol as compared to the saline controls. Levels of 5-HT and 5-HIAA in the brain tissues of rats treated with MDMA plus PBN were elevated as compared to those treated with MDMA plus saline. Similar results were observed in the density of 5-HT transporters in the frontal cortex and hippocampus. These results indicate that scavenging of free radicals of MDMA metabolites or reactive oxygen species by PBN and with lowering of body temperature protected against MDMA-induced depletion of serotonin transmitter. 相似文献
27.
Liver resection for hepatocellular carcinoma in octogenarians 总被引:4,自引:0,他引:4
BACKGROUND: Liver resection is risky in patients aged > or = 80 years. Because of short life expectancies and improved nonoperative modalities, the role of liver resection in octogenarians with hepatocellular carcinoma (HCC) is unclear. METHODS: A retrospective review of the operative results of 260 patients with HCC between 1991 and 1997 was performed. According to the age at the time of operation, these patients were divided into 2 groups. Group 1 comprised 21 patients aged > or = 80 years, and group 2 comprised the other 239 younger patients. The backgrounds, pathologic features of the tumor, and operative results of the patients were compared. RESULTS: Octogenarians had a higher incidence of associated medical diseases, a higher incidence of negative serum hepatitis B surface antigen, a lower alpha-fetoprotein level, and a higher indocyanine green retention rate. Although octogenarians had a longer postoperative hospital stay, there were no significant differences between the 2 groups regarding operative morbidity and mortality. The 5-year disease-free and actuarial survival rates for octogenarians and younger patients were 50.6% and 35.3% (P = .15) and 40.9% and 59.3% (P = .46), respectively. CONCLUSION: Under meticulous preoperative assessments and postoperative care, liver resection for HCC is justified in selected octogenarians, with short- and long-term results comparable to those of younger patients. 相似文献
28.
A 22-year-old man with malignant immunoblastic lymphoma had "locked-in" syndrome within 48 hours of receiving a single (100 mg) dose of intrathecal cytosine arabinoside (ara-C) in conjunction with intravenous ara-C, cisplatin, and doxorubicin. Eight hours after therapy, the patient had central hypoventilation and blurred vision that progressed to blindness within 3 hours. During the next 10 hours, he became completely quadriplegic but remained intermittently alert and was able to respond to commands by eye or head movements. Radiographic studies showed necrosis of the medulla and swelling of the entire spinal cord. The patient persisted in a locked-in state until his death 3 weeks later, after removal of life support systems. Autopsy confirmed extensive necrosis of the lower medulla, optic chiasm, cranial nerves I and IV, and spinal cord. This case was unusual for its severity. The temporal relationship to ara-C instillation favors a toxic idiosyncratic response to chemotherapy. The authors advocate caution when bolus intrathecal and intravenous ara-C are administered to a patient within a short time of each other. 相似文献
29.
Hypotension is an uncommon complication of procedures involving extracorporeal circulation, including plasmapheresis. From November 1993 to March 1999, we treated 139 patients who underwent a total of 1,137 sessions of double filtration plasmapheresis (DFP). Hypotension was defined as a systolic blood pressure (BP) < 80 mm Hg or any decrease of systolic BP with systemic reactions. A total of 17 (1.5%) episodes of hypotension were documented in 15 patients during the study period. Hypotensive episodes occurred in 2.3% of patients with inflammatory neuropathy, 1.2% of patients with myasthenia gravis, and 1.2% of patients with all other medical diseases. Involvement of the autonomic nerve system (ANS) and a low baseline BP were associated with the occurrence of hypotension. Eight (47%) of 17 episodes were symptomatic and 2 were complicated with seizure. Patients with symptomatic hypotension had a higher level of systolic BP prior to DFP and a larger drop of systolic BP and pulse rate during hypotensive attacks compared to asymptomatic patients. Most hypotensive episodes were resolved briefly after intravenous infusion of saline within 30 min. Eight (47%) of the hypotensive episodes occurred during the first session of DFP treatment. Twelve (71%) of 17 episodes occurred during the last half period of treatment; 6 of them were noted during the terminating stage of DFP. In conclusion, in this series plasmapheresis-related hypotension occurred in 1.5% of DFP sessions and had a higher prevalence in patients with ANS instability and low BP. Extra caution in monitoring BP during DFP therapy is warranted in these vulnerable patients, especially during the termination phase of the first DFP session. 相似文献
30.