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911.
Caro SP Balthazart J Thomas DW Lacroix A Chastel O Lambrechts MM 《General and comparative endocrinology》2005,140(1):52-60
Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the first results of such a study in two Corsican populations of a European passerine bird, the blue tit (Parus caeruleus). The two study populations occupy different oak habitats and are separated by only 25 km. Despite their close proximity, they show a one-month difference in onset of egg laying, even after controlling for altitude. This micro-geographic difference in breeding date appears adaptive because both study populations raise chicks when food is most plentiful. In our study, males reached their maximum song activity during the egg-laying stage while maximal testosterone levels and testes sizes were reached 2-3 weeks before egg laying. The rate of development of the reproductive system in males was much faster in the earlier population, in spite of a similar onset of gonad development and song activity for the two study populations. No change in the volume of the song-control nuclei (HVC and RA) could be detected during the study period. Development of brain nuclei was completed 2-3 months before the beginning of intense sexual activity. 相似文献
912.
- A scoring or cutting balloon is always useful in preventing slippage during therapy of in‐stent restenosis.
- A drug‐coated scoring balloon for in‐stent restenosis may be an alternative to a drug‐coated balloon
- Definitive comparison trials are needed and likely to help define their exact role in patients with in‐stent restenosis
913.
Novel features in the genetic code and codon reading patterns in Neurospora crassa mitochondria based on sequences of six mitochondrial tRNAs 总被引:37,自引:11,他引:37
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Joyce E. Heckman Joshua Sarnoff Birgit Alzner-DeWeerd Samuel Yin Uttam L. RajBhandary 《Proceedings of the National Academy of Sciences of the United States of America》1980,77(6):3159-3163
We report the sequences of Neurospora crassa mitochondrial alanine, leucine1, leucine2, threonine, tryptophan, and valine tRNAs. On the basis of the anticodon sequences of these tRNAs and of a glutamine tRNA, whose sequence analysis is nearly complete, we infer the following: (i) The N. crassa mitochondrial tRNA species for alanine, leucine2, threonine, and valine, amino acids that belong to four-codon families (GCN, CUN, ACN, and GUN, respectively; N = U, C, A, or G) all contain an unmodified U in the first position of the anticodon. In contrast, tRNA species for glutamine, leucine1, and tryptophan, amino acids that use codons ending in purines (CAGA, UUGA, and UGGA, respectively) contain a modified U derivative in the same position. These findings and the fact that we have not detected any other isoacceptor tRNAs for these amino acids suggest that N. crassa mitochondrial tRNAs containing U in the first position of the anticodon are capable of reading all four codons of a four-codon family whereas those containing a modified U are restricted to reading codons ending in A or G. Such an expanded codon-reading ability of certain mitochondrial tRNAs will explain how the mitochondrial protein-synthesizing system operates with a much lower number of tRNA species than do systems present in prokaryotes or in eukaryotic cytoplasm. (ii) The anticodon sequence of the N. crassa mitochondrial tryptophan tRNA is U*CA and not CCA or CmCA as is the case with tryptophan tRNAs from prokaryotes or from eukaryotic cytoplasm. Because a tRNA with U*CA in the anti-codon would be expected to read the codon UGA, as well as the normal tryptophan codon UGG, this suggests that in N. crassa mitochondria, as in yeast and in human mitochondria, UGA is a codon for tryptophan and not a signal for chain termination. (iii) The anticodon sequences of the two leucine tRNAs indicate that N. crassa mitochondria use both families of leucine codons (UUAG and CUN; N = U, C, A, or G) for leucine, in contrast to yeast mitochondria [Li, M. & Tzagoloff, A. (1979) Cell 18, 47-53] in which the CUA leucine codon and possibly the entire CUN family of leucine codons may be translated as threonine. 相似文献
914.
Measurement of cholesterol synthesis in man by isotope kinetics of squalene. 总被引:3,自引:2,他引:3
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G C Liu E H Ahrens Jr P H Schreibman P Samuel D J McNamara J R Crouse 《Proceedings of the National Academy of Sciences of the United States of America》1975,72(11):4612-4616
A method for measuring the rate of total daily cholesterol synthesis in man has been developed through isotope kinetic studies of squalene biosynthesis after intravenous administration of [14C]mevalonic acid. Plasma squalene becomes rapidly labeled, reaching maximal specific activity approximately 100 min after mevalonate administration and then decays exponentially to reach undetectable levels in 12 hr. The rate of daily squalene synthesis equals the percent dose of mevalonate converted to cholesterol divided by the area under the specific activity curve of squalene; the fraction of the dose of mevalonate converted to cholesterol is calculated by the simultaneous injection of [3H]- and [14C] cholesterol in plasma. The premise that squalene and cholesterol synthetic rates are equivalent was tested. In seven patients it was found that the mean daily cholesterol synthesis rates estimated simultaneously by sterol balance and by sqyalene kinetic methods agreed within 8%. In addition, fractional conversions of mevalonic acid to cholesterol were highly correlated with cholesterol synthesis rates. Maximum estimates of the pool sizes and half-lives of metabolically "active" squalene also were obtained. This measurement of daily cholesterol synthesis by squalene kinetics minimizes patient inconvenience, is suitable for outpatient studies, and yields results in 4 weeks or less. Because of the rapidity of the rate of squalene synthesis, the results obtained reflect cholesterol synthesis over a period of less than 10 hr and are therefore uniquely applicable to unsteady state situations. 相似文献
915.
Dodic M Samuel C Moritz K Wintour EM Morgan J Grigg L Wong J 《Circulation research》2001,89(7):623-629
We have shown that exposure of pregnant ewes to dexamethasone (11.5 mg/d for 2 days) at 27 days of gestation (term, 150 days) led to increased blood pressure and cardiac output in adult offspring. In this study, we hypothesized that dexamethasone-induced hypertension is associated with left ventricular hypertrophy and a reduced cardiac functional reserve (CO(max-0)). Six control animals (group C) and five dexamethasone-exposed animals (group D) were volume-loaded with Hemaccel until the wedge pressure was 13 mm Hg (baseline). The wedge pressure was held constant during an infusion of dobutamine at incremental doses (0.4 to 12 microgram/kg/min) while blood pressure and cardiac output were measured. The same protocol was repeated in each animal 5 days later under mild general anesthesia (1.5% isoflurane), when transthoracic echocardiography (M-mode) was obtained. Group D showed a reduced CO(max-0) in response to dobutamine during both conscious (89+/-22 versus 150+/-25 mL/kg/min in control; P<0.01) and anesthetized states (91+/-38 versus 156+/-56 mL/kg/min in control; P<0.05). Reduced CO(max-0) in group D was associated with higher left ventricular mass index compared with group C (2.6+/-0.67 versus 1.8+/-0.51 g/kg; P<0.05). In addition, group D showed a reduced cardiac contractility reserve (FS(max-0)) in response to dobutamine (21+/-22% versus 54+/-34% in group C; P<0.05). An impaired cardiac functional reserve in group D was associated with increased left ventricular type I collagen content. In conclusion, brief prenatal exposure to dexamethasone led to the development of hypertension, left ventricular hypertrophy, and reduced cardiac functional reserve in adult life. 相似文献
916.
Sia SK Kim PS 《Proceedings of the National Academy of Sciences of the United States of America》2003,100(17):9756-9761
Protein grafting, the transfer of a binding epitope of one ligand onto the surface of another protein, is a potentially powerful technique for presenting peptides in preformed and active three-dimensional conformations. Its utility, however, has been limited by low biological activity of the designed ligands and low tolerance of the protein scaffolds to surface substitutions. Here, we graft the complete binding epitope (19 nonconsecutive amino acids with a solvent-accessible surface area of >2,000 A2) of an HIV-1 C-peptide, which is derived from the C-terminal region of HIV-1 gp41 and potently inhibits HIV-1 entry into cells, onto the surface of a GCN4 leucine zipper. The designed peptide, named C34coil, displays a potent antiviral activity approaching that of the native ligand. Moreover, whereas the linear C-peptide is unstructured and sensitive to degradation by proteases, C34coil is well structured, conformationally stable, and exhibits increased resistance to proteolytic degradation compared with the linear peptide. In addition to being a structured antiviral inhibitor, C34coil may also serve as the basis for the development of an alternative class of immunogens. This study demonstrates that "one-shot" protein grafting, without subsequent rounds of optimization, can be used to create ligands with structural conformations and improved biomedical properties. 相似文献
917.
Carlos Eduardo Pouey da Cunha Samuel Rodrigues Felix Amilton Clair Pinto Seixas Neto Anelize Campello-Felix Frederico Schmitt Kremer Leonardo Garcia Monte Marta Gon?alves Amaral Márcia de Oliveira Nobre éverton Fagonde da Silva Cláudia Pinho Hartleben Alan John Alexander McBride Odir Antonio Dellagostin 《The American journal of tropical medicine and hygiene》2016,94(3):519-521
Leptospirosis is a global zoonosis caused by pathogenic Leptospira spp. In this study, we characterized two Leptospira kirschneri serogroup Pomona serovar Mozdok isolates, one obtained from a dog and the other from a patient with severe leptospirosis, 4 years later. Histopathological analysis showed that both isolates caused severe tissue damage when used to infect hamsters. While L. kirschneri serogroup Pomona serovar Mozdok is endemic in animals in Europe, there is only one report of human leptospirosis in the literature. Although strains belonging to L. kirschneri serogroup Pomona have been identified in cases of human leptospirosis in Europe, serovar Mozdok has not yet been implicated. The 4-year interval between isolations and the fact that this is the first report of serovar Mozdok as the causative agent of human leptospirosis in the southern hemisphere, demonstrates its epidemiological importance to public health. Moreover, the presence of serovar Mozdok in Brazil has the potential to affect vaccine and diagnostic test development.Leptospirosis is a reemerging zoonotic disease, and the global burden is showing an upward trend. The original estimates in 19991 predicted some 500,000 annual cases compared with the latest prediction of 873,000 cases and 49,000 mortalities per year, a 74.6% increase over 15 years.2 Accurate laboratory diagnosis continues to be a limiting factor, meaning that the true global burden of leptospirosis is likely to be much higher.3 In Latin America, the prevalence of severe leptospirosis is high (10,000 cases a year) due to the tropical climate and lack of appropriate sanitation.3 Although the city of Pelotas has a subtropical climate, > 50 cases of human leptospirosis per 100,000 inhabitants are reported each year, one of the highest rates in southern Brazil.4 The infection rate in Pelotas is higher than the Brazilian average for the same period (3.5/100,000) and other regions with similar climatic conditions (> 10/100,000).5At present, there are 10 pathogenic Leptospira spp. classified into > 260 serovars6 and Leptospira interrogans, Leptospira borgpetersenii, and Leptospira kirschneri are most commonly associated with human leptospirosis.7 In Brazil, L. interrogans serogroup Icterohaemorrhagiae serovars Icterohaemorrhagiae and Copenhageni are the main cause of urban leptospirosis and have been widely studied,3 whereas rural leptospirosis and the associated serovars have been largely neglected. To the best of our knowledge, L. kirschneri serogroup Pomona serovar Mozdok has only been implicated in a case of human leptospirosis in Cuba.8 Serovar Mozdok is endemic to Croatia where it is prevalent in wild rodents. Human leptospirosis caused by serogroup Pomona is common in that region and while serovar Mozdok has not been implicated in any human cases,9 it is a causative agent of canine leptospirosis in Europe.10We report the isolation and characterization of two isolates of serovar Mozdok recovered from cases of canine and human leptospirosis in Pelotas, southern Brazil. The canine strain was isolated in 2009 during a municipal dog neutering campaign. Urine samples were aseptically collected from the bladder during ovarian hysterectomy, via aspiration using an insulin 30-G needle and syringe (BD Biosciences, Franklin Lakes, NJ). The urine was immediately inoculated into unsupplemented Ellinghausen-McCullough-Johnson-Harris (EMJH; Difco, Sparks, MD) medium (100 μL urine/5 mL EMJH), incubated for 1 hour and then subcultured into EMJH containing 10% of a commercial supplement (Difco). The dog from which the strain was isolated was asymptomatic and was released after the surgical procedure. The second isolate was obtained from the blood culture of a 56-year-old female patient from a rural area of the city. The patient presented with headache, myalgia, fever, vomiting, fatigue, sleepiness, and arthralgia and reported contact with dogs, rats, pigs, cattle, and flood water. The isolate was cultured in EMJH medium as described for the canine isolate. Both isolates were identified as L. kirschneri by means of secY gene sequencing.11 Multilocus sequence typing (MLST)7 further characterized the isolates as L. kirschneri serogroup Pomona serovar Mozdok (ST 117). All sequencing procedures were performed using the paired-end technology on an Illumina Solexa platform (Illumina, San Diego, CA; GenBank accession numbers for sequences are shown in Gene Isolate 61H Isolate 3759 mreA KP114449 KP125524 glmU KP114450 KP125525 caiB KP114451 KP125526 pfkB KP114452 KP125527 pntA KP114453 KP125528 sucA KP114454 KP125529 tpiA KP114455 KP125530 secY KP114457 KP125532